Crazy acres

Of all the traditions that are kept alive today the acre for land measurement has to be one of the daftest.

(Article by Phil Hall)

To begin with hardly anybody today really knows what an acre is let alone where it came from. Yet we see and hear it being quoted all the time in respect of land area both for housing and even industrial purposes.

So what is an acre? Well anyone could look it up in a table of conversions and find it listed as 4840 square yard, but why this peculiar number? Furthermore how come it isn’t a square number? (The square root of 4840 = 69.5701085 …)

It is in fact the area of a strip of land 1 chain wide by 1 furlong in length, where a chain is 22 yards and a furlong is 10 chains (hence 22 x 220 = 4840). According to popular history this is an estimate of how much land a farmer could till in a day with a horse drawn plough. Now that the reader knows this I’m sure it’s relevance to modern applications will become clear!

The proper metric unit of area is of course the square metre, but since it is rather small for land area of any size a unit known as the hectare has come into general use. It is quite simply a square 100 m by 100 m The name derives in fact from a contraction of the prefix hecto (x 100) applied to another metric unit of area known as the ‘are’ (prounced air) which is a square 10 m by 10 m This latter unit is rarely used nowadays.

The arithmetic is remarkably logical and simple. 100 square metres = 1 are, 100 are = 1 hectare, 100 hectare = 1 square kilometre.

With the demise of the ‘are’ the hectare is now better known as being 10 000 square metres.

The sadest thing of all about the retention of the acre is that it does nothing to help people understand the concept of area and how we measure it. Nothing could be more awkward than a rectangle 10 times as long as it is wide as means of guaging it even if that fact is known.

In truth it is more likely that when information about modern developments are quoted in acres it has actually been worked out in hectares and converted using the factor 1 hectare = 2.47 acre. A classic case of taking something easy and making it hard.

Author: UK Metric Association

Campaigning for a single, rational system of measurement

33 thoughts on “Crazy acres”

  1. When I was a young town planning assistant in the 1960s, one of my most tedious jobs was measuring the areas of building sites in square feet (not yards, by the way), converting these sums into acres and then, as a check, aggregating them into grid squares on the 1:1250 scale ordnance survey sheet. The instrument used was a “planimeter”, which required a conversion factor according to which scale you were working at. All this was done manually by long multiplication and division (there were no electronic calculators, let alone computers in those days – although a slide rule could be used for approximations). As there are 43 560 sq ft in an acre, and 640 acres in a square mile, the horrendous nature of the calculations can be imagined.

    I was overjoyed therefore when I learnt that the UK was to convert to metric system by 1975, and we could adopt the logical simplicity of square metres, hectares and square kilometres. What bliss!

    Sadly, owing to the timidity and political cowardice of our politicians and civil servants over the last 42 years, we are still stuck with the mess of two systems of measurement, and very few people could even begin to calculate an area of land in either acres or hectares. What an indictment of a supposedly modern country!


  2. The Scottish acre was standardised in 1661 and abolished in 1824. It had an area of 4870 m² instead of the English acre’s 4047 m². It is also worth noting that the German word for a “field� is “acker�.

    The abolition of the Scottish acre was part of a standardisation of weights and measures that was being carried out by the British Government at the time – the Imperial Gallon dates from that era. Unfortunately the British Government was run by people who today would be called “Eurosceptics� and who appeared to by trying to develop a “British decimal system� – why else would the gallon be defined as the volume of 10 lbs of water? The British Government cannot plead ignorance – four years previously across the North Sea, the Dutch, on realising that every city had its own “voet� (foot) and “pond� (pound), had standardised on the metric system.


  3. Acres are one of those strange measures, like “size of a football pitch”, that crop up in the media, and I have no idea how big either is. Therefore I’m somewhat disappointed that a pro-metric website is trying to force the arcane numbers that seemingly define an acre into my head: I have no room for such trivia! The whole point of the metric system is that you do not *need* to waste time recalling random numbers to work out how large something is.

    All I need to know is that the definition of an acre is indeed arcane (and certainly not a nicely-square unit of area in its simplest form) and a reminder that we do have perfectly sensible – and easily-convertible – units of area: the m², the hectare, and the km².

    So the question is, why doesn’t the media use hectares as a description more often? As a simple 100×100 m square, it can be easily visualised and understood. And as the author notes, 10x 10 hectares = 1 km², what could be simpler?


  4. In response to David, I don’t think this article is trying to fo”force arcane numbers” into your head, but illustrate just how daft this particular measure is. I too am also frustrated by media reports that compare things to the “size of a football pitch”, especially since British football pitches aren’t (or at least never used to be!) the same size, unlike the US “Football Field” which, like in most US professional sports, is a fixed size.

    I spent a couple of days last week scanning through a number of news stories on the BBC news web site and found no consistency in the way that they use acre and hectare, but this is the same in the real world where you can drive past commercial construction sites to see billboards advertising warehouse space, some in square metres and others in square feet. If I were looking for space to run a business I’m sure I’d be quite bemused at having to keep converting from one to the other to make comparisons. On the same basis it’s no wonder that we have to use comparisons like football pitches, busses and jumbo jets so that joe public can get a feel for the size of an object… no sooner than people get used to what a metre looks like, the next thing they know is that they’re being bombarded with feet again!

    I think this all goes to prove that unless we have legislation to force the use of one type or measurement, even if it’s only temporary, this mess will just continue!


  5. An are (a) is a square dekametre (dam²) and a hectare (ha) is a square hectometre (hm²), by the way, and a centiare (ca) is a square metre (m²). 😉


  6. I visualize an acre as 4000 m^2. Since it was originally defined as an area of land that can be ploughed in a day, then there is no reason it can’t be thought of as a nice rounded number in metric. This can easily be thought of as any number of combinations of metres by metres.

    A 50 x 80 m plot would be the closest to a square using rounded numbers.

    I live on a typical one quarter acre lot in a suburban sub-division. this would be a 1000 m^2 lot. I measured it once with a tape measure and it was very close to 20 m 50 m.

    It seems the acre might work better with metric then with FFU.

    I wonder if those who cling to FFU do so because they like the names. So why not recycle the names as slang terms for metric units. Yards and quarts can disappear and be replaced by metre and litre. There is no need to have two units for the same name.

    A pound can be 500 g, a mile can be 2 km, a pint 500 mL (a good compromise between the US and UK version), a gallon can be 5 L, etc. The old units names are still found in other EU states but the old meanings are long gone. If the UK followed the practice of the Continent in regards to old unit names, then there might not be such a fuss.

    Who quibbles when they go to France and gets 500 g when a pound (livre) is requested, or 500 mL when a pint is requested? So why should they quibble if it is done in the UK?


  7. Does this mean that Winnie the Pooh will now live in the ‘40.46 Hectare Wood’? I hope not!


  8. I have to say, I chanced upon this looking for a converter: square metres to acres – and it’s fantastic I did.
    I’m from Australia where the acre has already invaded the land and real estate industries, and sadly society’s consciousness.

    And yet now, thanks to you Phil Hall, it all makes such simple sense.

    Out with the acre – it seems so ridiculous that it is used.
    Bring back the hectare – 100 m x 100 m!!

    Great article!!


  9. As an expat Brit living in the US, I’m back in the world of imperial measurements in official, not just conversational use. And since Americans love talking about land and house lots and other property-related guff, I have to plead ignorance. I’m in my mid-30s, and it’s taken me until now to visualise an acre.

    (Basically, think ‘a bit bigger than half a UEFA-approved football pitch’.)


  10. To Phil Hall’s comments about the use of the acre, this might help to explain things.
    I was brought up with the old imperial system, and a guinea/pounds/crown/florin/shillings/pence/halfpenny/farthing monetary system which was rammed down my throat at school while at the same time my teacher slapped me with a 12-inch ruler everytime I got it wrong (which was quite often). It also had “10 mm = 1 cm, 10 cm = 1dm, 10 dm = 1 metre” etc printed on it, for our information.
    I thought there must be some logic in this, as Britain was supposed to be the greatest country in the world at the time, and head of a huge Commonwealth to boot.
    So I soon learned that Britain was actually made up of eccentric people who thrived on confusion, illogic, silliness and a railway system and society that was modelled on Emmet’s Railway.
    Why change the system if all the people are happy with an illogical system of measures? It was no surprise to learn that many people were upset when the Banks decided to change the money to a (shudder) ‘decimal’ system and everyone thought that items in shops were going to unaffordable after conversion. So to keep people happy, the Banks retained a “half p” coin and the Post Office even produced a “half p” stamp.
    Confusion surely lasted long after conversion because people continued to try to convert decimal values to pre-decimal values and soon they realized that they were wasting their time when 50p always was going to be 50p.
    Then the petrol stations switched from showing gallons to litres and then the expletive really hit the proverbial fan.
    This surely must mean that the Belgian army is going to march down Whitehall soon, and take over the Houses of Parliament.
    Not once was there any thought that Britain was modernizing itself, or that it was preparing itself to be part of the world in the 21st century, when Britain’s heritage was so much at stake. The Editor of ‘This England’ magazine even started a movement to ban the use of the metric system altogether, and anything to do with Europe.
    If Britain’s heritage was so much at stake, why were people so keen to trade in their horse and carts for the latest Japanese, Swedish or German car?
    So with this kind of mentality present in today’s Britain, may I propose that imperial units reign forever and the good old perch be adopted for land areas to make it so much easier for everyone, and that bridge heights always remain in feet and inches so that many more French truck drivers can be decapitated under low bridges who haven’t got the necessary speed or gumption to do the necessary calculations in time?
    I now live in Australia and its boring old system of logical values, and I sure miss all that eccentricity and silliness for the sake of ‘heritage’ back in the old country – the VERY old country.
    Toodle pip,


  11. “Buy an Acre” World Land Trust (WLT) is saving threatened habitats acre by acre, creating protected nature reserves across the world.
    See link:

    YES CRAZY, – the reason acres are used instead of hectares is probably because the headquarters is in the UK.
    World Land Trust
    Blyth House, Bridge Street
    Suffolk, IP19 8AB

    Patrons of the World Land Trust (WLT) are Sir David Attenborough, David Gower OBE and Chris Packham.


  12. @Mary
    Oh dear, what an awful article that is!
    I wonder who wrote that mess. Chris Packham for one is the most metric person on TV, he would have had no input in that I am sure. Sir David is also very metric in later years.
    They do give an explanation as to what an acre is, referenced to football fields, tennis courts, Wales, many things in England and …oh my square YARDS!!! NOTHING in metric! 50 years of UK education? 50 years of metric in the high street? What a pathetic waste of 50 years government.
    Little England, saving the world inch by inch!


  13. @BrianAC
    What are your views on the idea of freedom of expression? If someone thinks in imperial, and their culture and heritage has given them imperial tendencies, then why not allow them to express themselves in imperial? Especially if the other members of their association and their target audience are also mostly similarly infused.


  14. The figures are slightly deceptive. They do mention the area in square meters in parentheses, but in all the countries where they say they are working, I am quite sure the legal unit for surveying is meters. The real price is £250/ha and “acre” is just a cute name for 0.4 ha, not 43560 ft². The error is probably not sufficient to rise to the level of fraud, but at least deceptive.


  15. Why does “cultural heritage” keep being used as an excuse?

    Invading other countries and making them part of our “empire” was our cultural heritage?

    The sale and transportation of people for slavery was our cultural heritage?

    Not allowing women to vote was our cultural heritage?

    Imprisoning people for their personal sexual preferences was our cultural heritage?

    Counting money in pounds, shillings and pence was our cultural heritage?

    Just because we, as a country, have always done something in a particular manner it doesn’t make it right and using culture is only an excuse when you can think of nothing better (in the same way as being “offended” by something).

    Sometimes we have to change to make things better, and frankly I’d prefer my cultural heritage to be one of embracing change when it’s right and leaving bad things from the past behind us. If I wanted to live in a museum I’d ask to rent a room at the V&A!


  16. @Alex
    You misrepresent my point. One’s culture and heritage may result in one using a certain language or dressing a certain way or using certain measurement units. That isn’t a fault or failing in one, so does not require an excuse. To say that “cultural heritage” is being used as an “excuse” is, frankly, insulting and disgraceful. Would you insist that the French adopt English as their official language because their culture and heritage is no excuse not to?


  17. Charlie P says: 2015-05-28 at 11:32
    @BrianAC What are your views on the idea of freedom of expression?

    Sorry if I am wrong Charlie, but I thought that was my freedom of expression. What is yours? It is OK for me to have freedom of expression so long as it agrees with you.

    We have gone through all this before. The answers will be the same. You are on a loosing wicket.


  18. @ Charlie P says: 2015-05-28 at 11:32
    “Especially if the other members of their association and their target audience are also mostly similarly infused.”

    This article is my opinion, my freedom of expression.
    You have hit the nail right on the head here. I am (or would have been), one of the target audience. The WORLD – THE WORLD – the WORLD Land Trust, not the little england land trust. THE WORLD is not infused in Imperial culture. Back here in little england, people that use the countryside are not (for the most part) infused in Imperial culture.

    If you ever walk or cycle in the countryside you would use an OS map. Even OS use the phrase ‘in the real world! So, from the real world of the OS web site (“The OS Explorer Map (the orange one) – is at 1: 25 000 scale (so 4cm on the map equals 1km in the real world)” or “The OS Landranger Map (the pink one) – is at 1: 50 000 scale (so 2cm on the map equals 1km in the real world)”).

    They do however still include a little panel 295 mm x 9 mm for you to convert to miles if you so wish.

    Walkers and cyclists will for the most part use metric (in UK), the rest of the WORLD (if we exclude USA) uses metric anyway. The target audience here would be those that do get out of the car and into the countryside, where metric prevails.

    If you need some ‘hard evidence’ Charlie then tune into BBC one and watch ‘Springwatch’, it is on for another two weeks I think, (or use your i-player). There you will see (and hear) Chris Packham (one cited in this article) in his natural environment, he did one night this week give a distance in miles with the phrase “… for those still using Imperial that is about 58 miles …” (episode 1, Swallow migration, 54th minute), For the most part it is all metric, square metres, square km (Minsmere reserve is 10 km²). Most distances are given in metres, by the three main presenters at least. This programme has a large audience, and a participating audience at that as it is interactive, the target audience are those of us that live is the real world, outside the car doors.

    Now, on the practical side, WLT cannot buy an acre of land in Mexico, to say they do is a misleading statement, make believe, a lie. There are many of these listed, including those in UK. Land in UK is not bought and sold in acres. It is a fabrication of lies from start to finish. This would only hold true in USA, but that is a different world altogether. It is not a good way to raise charitable funds.


  19. @BrianAC

    In the US, road maps use miles and land is sold in acres (square feet for smaller parcels). However, US topographical maps are primarily metric and marked in UTM coordinates (or US National Grid, which assigns two-letter names to 100 km squares and starts the easting and northing coordinates over in each southwest corner. The tiling names for 100 km squares are a different sequence, but the numeric coordinates are the same as Ordnance Survey usage). Hikers, hunters, fisherman, bikers would tend to use those as their main map.


  20. In Australia the land was originally surveyed in imperial measures, but now it is increasingly advertised in square metres for smaller areas and hectares for larger areas. However, acres do persist, especially for rural land, though usually the hectares are provided if a property is advertised in acres and often acres are provided if the land is advertised in hectares. See


  21. @BrianAC
    You misrepresented my point as: “It is OK for me to have freedom of expression so long as it agrees with you.”

    The tenet here is to suppress the freedom of others to express sizes in whatever units they choose, and it is that that I am pointing out. You are, of course, free to express units in whatever units *you* choose. It is disingenuous to suggest that I meant anything different.


  22. @BrianAC
    You claim the target audience is the world and that the world “is not infused in Imperial culture.” Well the website, as far as I can see, only provides the facility for UK and US purchases. We know that acres are far from alien measures to the British and, as we have seen from John Steele, land is also sold in acres in the US. Even the good folk of the Commonwealth country often often cited as having been one of the most successful in its metrication efforts, Australia, still use acres in land sales (according to Michael Glass). So we see the units chosen are perfectly valid for the target audience, and there is no apparent logically valid reason to criticise their choice.


  23. @Charlie P If you feel insulted by my comments on “culture” then so be it… but the human race continues to exist not because of its ability to cling onto the past no matter what but because of its ability to invent and improve on what came before. To evolve if you wish. You may say that we don’t want to force the French to speak English however in the world of business it is often expected that to trade with your international partners you have to leave your own language behind and in many cases English is the language of choice – especially where safety is paramount hence why air traffic controllers and airline pilots use English.

    But then taking language as an example, the English language we speak today differs in many ways from that we would have spoken 100 years ago, indeed you and I would probably find it hard to understand spoken English from just a few centuries ago. Our language has evolved from many others across Europe including Roman/Latin, French, German, Danish, etc. So has our language, spoken or otherwise, remained the same because it’s part of our culture? No it hasn’t, it has evolved and changed to suit our needs. People complain when words from other English dialects creep in but that’s part of the change and evolution of our language and other languages evolve in the same way. Culture be damned.

    If we as a country have any chance of remaining significant in a shrinking world we have to embrace change when it’s the sensible thing to do, not make excuses to resist it. I make no apologies for saying that if “culture” is about retaining the past at the expense of the present and the future then I want nothing to do with it as it’s nothing more than an excuse to hold our country and our descendants back.


  24. @Alex
    You have reinforced my point exquisitely. The UK are, with metrication, roughly where the French are with the English language. They teach it to all pupils in their schools, as a nation they are perfectly competent in its use, but they choose only to use it where it is essential for business, commerce and legality. As with the French people and the English language, the British people are, currently, unlikely to drop their culture, heritage and tradition to embrace the metric system to facilitate international harmonisation.

    Who knows what will happen in the future though as globalisation continues. And with US culture creep continuing at its current pace, fuelled by the dominance of US movies, TV programmes and media, perhaps the French will end up speaking English, probably US English (which the Brits are moving towards too).

    But if we do not protect our local culture and traditions, not only will we all be speaking US English, but perhaps we will all end up using US customary weights and measures too! Be careful, very careful, of what you wish for!!


  25. I’m with you, Charlie. I standardize wherever and whenever I have to, but I LOATHE the conceit that everybody has to use the same measures, or all schools must be under one point of control, or that politics MUST be global. I live my life at the village level, in a little town with plots all measured in acres. The system works. I don’t feel compelled to convert my holding into hectares just because it is the logical and modern things to do. We do fine with quarts and half gallons as well, and even “get it” that these volumes are also listed in fractions of liters. It’s not a big deal. I visited this site to chase down the origin of the unit “acre” and learned what I wanted to. Thanks. Horses, by the way, are also sometimes mentioned as being so many “hands” tall. Will the thought police and frogs in Belgium throw up their hands in horror at the thought and insist we use an “official” metric conversion for the “hand”?


  26. Whatever might be said about tradition, we really do need to have one measure for common items. It’s a pain in the neck to have rural land advertised in both acres and hectares, to have the sizes of jeans and some trousers measured in inches while others are measured in centimetres, to have tyre pressures in both psi and kPa, to have shoes in American, UK and also in Continental fittings, to try to find the right size of belt and discover that some are labelled S, M and L, others are in centimetres and yet others are in inches.

    800 years ago the Magna Carta said there should be one measure. It made sense then and it still makes sense today.


  27. Kevin says: 2016-01-29 at 16:44
    “… We do fine with quarts and half gallons as well, and even “get it” that these volumes are also listed in fractions of liters. …”

    Quarts in England?


  28. I know what a square yard looks like it. I do remember my small plot of land, 3×3 square feet, with four short posts at the corners. A wire connected said posts all around. Within this area was the tilled soil (I did that) in which my lawn seeds were sewn (I did that too). My very first lesson in agriculture at the tender age of about five! Oh, yes – my dog and I had many a picnic lunch on this lovely piece of green, eighty-six happy years ago.


  29. @Emily Arnold:

    I hate to break it to you, but the imperial yard was changed slightly—57 indifferent years ago—so you might not be as reliable with your imperial square yards as you once were. Plus, you’d need a lot of wire, posts and patience for a whole acre. Then you shall discover that there are several different versions of the `acre’ which you might encounter and wish you’d stuck with the dog picnics instead ;-).

    This is part of the reason why Dr. Metric asks the question `how big is an acre?’ and correctly identifies the answer `nobody knows’.


  30. Mark,

    You can always envision an acre as exactly 4000 m^2 (200 m x 20 m). Since the typical British garden allotment is exactly 250 m^2, an acre would be 16 allotments, or 4 x 4 allotments. A quarter acre lot would be 1000 m^2 or 50 m deep by 20 m wide.

    An acre is much easier to work with when thought of as a quasi-metric unit and not imperial.


  31. @Daniel Jackson:

    Good grief, yet another version of the `acre’ for Emily to disambiguate. I’ll stick with straightforward SI—and [hect]ares, as a last resort—thanks all the same. IME, the only people who try to fob anyone off with acres in the UK these days are residential estate agents and they seem unwilling to martyr themselves when asked what the actual area is (as per Land Registry title plan)…

    My advice to you is: don’t envision acres, it only encourages them!

    p.s. As an aside for UK TV viewers, from 2016-10-26, BBC FOUR is repeating Prof. Marcus du Sautoy’s series `Precision: The Measure of All Things’.


  32. @ Mark,

    You missed my point. Yes, acres must go, but there are too many people who wish to continue to use them even if they themselves don’t understand them. So when they speak them to you, you can either ignore them or insist they respond in metric terms.

    To which they can either ignore you or claim they don’t know. So, to make it easy for yourself, you can easily convert it your self assuming 4000 m^2 is an acre. So if they tell you something about blah blah 20 acres, you blurt right back, “don’t you mean 80 000 m^2 or simply 8 ha”?

    You are never going to get away from old school measuring words. They will persist for some time, but to make it simpler, the old words should be recycled in to slang metric units. A pound of 500 g, a pint of 500 or maybe 600 mL, a mile of 1600 m, just as an example.

    The French went fully metric in 1840, but the livre is still spoken today, but not an issue. The shop advertises in grams only and the product’s mass is determined in grams only, so when a livre is requested, 500 g is vended and sold. No one is running to the press demanding livre scales to return. Maintaining a pound of 454 g makes it impossible to relate pounds to grams and so you see the backlash where some aged customers want to buy in pounds. You may still run into some resistance with a 500 g pound, but a lot less than with a 454 g pound.


  33. @Daniel Jackson:

    Now you’ve explained your point, I think this does not `make it simpler’. AFAIK, in UK, nobody uses acres for any official purpose nowadays. It is another one of those areas (pun intended) where we are far ahead of USA in metricating. There may be many reasons for that. Here there are effectively no serious `people who wish to continue to use them’. Not in idle chatter amongst people on the street and not between professionals. The habitually anti-metric media, including TV entertainment programmes, mention them at every opportunity for purely ideological reasons but only allegorically and without any apparent expectation that the audience will understand them quantitatively. You say they `must go’, but are actually suggesting bringing them back from the dead and putting them on permanent life-support! What next: imperial gallons and grey squirrel `quarts’?

    Livres are a one-way linguistic shortcut in France and not necessarily one to emulate, precisely because of their persistence. One asks for a demi-livre of something, the shopkeeper will aim for 250 g but neither they nor the shopper will translate the difference from the measured amount back into livres. Slightly off-topic in this post, but I agree with you about the 454 g (or 4047 m² for allegedly `international’ acre) part. Co-incidentally, 450 g jars of confiture are very common in Northern France—possibly as a result of trade with UK—but give way to 500 g and 1 kg in the South.

    What you are proposing for acres, [pounds,] pints and miles sounds much more favourable to two-way convertibility, voluntary `duelling with dual’ adoption and indefinitely long transition periods. In that case; 600, 1600 and 4000 are also a hindrance to quick decimal reckoning and therefore complete metrication. You might gain more traction with 500, 2000 and 5000 (or better yet; 1000, 1000 and 1000) respectively.


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