One of the least known metric units – and one which journalists and estate agents seem to struggle with – is the hectare (ha). So perhaps it will help to relate this very useful measure to the sizes of sports fields. Article (including diagrams) by Martin V.

Q: How big is a hectare?

A: 10 000 square metres.

Q: How big is that?

A: It is the equivalent of a square, each side having a length of 100 m.

Q: What does that look like?

Many sports fields have an area that is comparable to a hectare. In some sports the size of the field is fixed; in others, the size of the field can be adjusted within limits to suit the land that is available. This article lists a number of sports whose fields are of the order of a hectare in size. The associated diagrams are all at the same scale (1:20 000 originally, but may look different on screen).

**Athletics **(Typically 1.2 ha inside the track)

The International Amateur Athletic Association has laid down the rules for athletic tracks that are used in competitions An athletics track is 400 m long (measured 20 cm from inside perimeter). The IAAF does not define the length of the straight section. If this section is 50 m, then the area inside the track is 1.194 ha (shown in green on the associated diagram). If the straight section is shorter, then the area increases until eventually we have a perfect circle which would have an area of 1.27 ha.

**Football **(International size: 0.62 ha to 0.82 ha)

The Federation Internationale de Football Association (FIFA) dictate that for international matches, the length of the pitch shall be between 100 m and 110 m and its width shall be between 64 m and 75 m. The smallest international football field is therefore 0.62 ha and the largest international football field in 0.82 ha. Non-international matches may be played on fields between 90 m and 120 m long and 45 m and 90 m wide.

**Cricket** (Typically 1.25 ha; Lords 1.43 ha)

The laws of cricket are maintained by the Marylebone Cricket Club (MCC). This only specifies the length of the cricket pitch (20.12 m); it does not specify the distance of the boundary from the pitch. Lords Cricket Ground, the home of the MCC, is played on a rectangular field 136 m long and 109 m wide with well-rounded corners. After allowing for corners having been rounded, it has an area of 1.43 ha. The cricket ground at the author’s home town is roughly circular and is typical of many cricket fields up and down the country. The author has paced the boundary and found it to be about 400 m. If it is assumed to be circular with a perimeter of exactly 400 m, its area would be 1.27 ha. The associated diagram is typical of many club fields and not of Lords.

**Rugby** (International size: 1.008 ha)

The laws and regulations of rugby dictate the maximum size of rugby fields; international matches are invariably played on fields that are of maximum size. The maximum width of a rugby field is 70 m and the maximum length between the goal posts is 100 m. In addition there is a ‘in-goal area’ that extends a maximum of 22 m behind the goal line. Thus the maximum size of the field is a rectangle 144 m in length and 70 m in width giving an area of 10080 m² (which is just over 1 ha).

**Baseball** (Between 0.83 ha and 1.12 ha)

The field dimensions used in Major League Baseball MLB) are laid down in the Official Rules. The exact shape of the outfield varies from field to field, but using the layout shown in the above diagram, the area of Major League Baseball fields can be shown to vary between 0.83 ha and 1.12 ha. The rules of the MLB do not apply to other leagues and so in areas where land is at a premium, the fields in lower leagues might be smaller than the minimum in the MBL.

References:

Athletics – www.iaaf.org/newsfiles/23484.pdf

Baseball – http://mlb.mlb.com/mlb/official_info/official_rules/foreword.jsp

Cricket – www.lords.org/laws-and-spirit/laws-of-cricket/laws/

Rugby – http://www.irb.com/lawregulations/index.html

Football – http://www.fifa.com/worldfootball/lawsofthegame.html

*[Strictly speaking the hectare is not part of the International System of Units (as it is a non-standard term for 10 000 square metres). However, it is useful to have a unit intermediate between the square metre and the square kilometre , and the hectare is accepted for use with the International System. It is in widespread use in other countries that use the metric system - Ed]*

This is a very good article. For people to visualize smaller areas of land the following table of information may be useful

100 m x 100 m Â Â Â 10 000 square metres Â Â Â 1 hectare

100 m x 50 m Â Â Â Â Â 5 000 square metresÂ Â Â Â Â Â½ hectare

100 m x 25 mÂ Â Â Â Â Â Â 2 500 square metresÂ Â Â Â Â Â¼ hectare

50 m x 50 mÂ Â Â Â Â Â Â Â Â 2 500 square metresÂ Â Â Â Â Â¼ hectare

It’s sad that many Estate Agents (Real Estate Companies) use acres not hectares. I think it’s far more difficult to estimate land areas with reasonable accuracy if acres are used.

To estimate these land areas in hectares people can think of their favourite sports field from the above list. Another way is to think of rectangular shaped ‘blocks’ of land with sides the length of a 100 metre running track, or the length of a non-olympic swimming pool which is often 25 metres.

The maths is straight forward, however be careful not to get confused with the language as the following example illustrates:

A square with sides each 10 metres long has an area of 100 square metres.

A square with an area of 10 square metres will have four sides each 3.1623 metres long. (The square root of 10 is approximately 3.1623).

Philip Bladon http://www.simetricmatters.com

An acre is more understandable to a metric user then an imperial user. Ask anyone who uses imperial how big an acre is and you will most likely get a funny look.

To a metric user, it is 4000 m^2. This can be thought of as 50 m x 80 m.

To those that live on a quarter acre lot, this is 1000 m^2 or 50 m a 20 m.

Not quite a harmonized metric unit, but at least it has more meaning to a metric person then an imperial one.

In response to Daniel – perhaps if I sit and think about it the acre is easily understandable in metric, but it still remains the fact that the acre is based on a rectangle with uneven edges where the hectare is a nice clean 100 x 100.

That said, if you’re looking at sporting “fields” then you generally have a rectangle anyway. In the case of my favourite sport , (ice) hockey, the rink size generally used in the international game (not the NHL though) is 30 m x 60 m which is about 0.18 hectare – although that doesn’t take into account the rounded edges of the rink!

I am astonished that in the UK we have not embraced the hectare. Almost everybody talks about acres without having a clear idea of what they are. OK, if a house is for sale with an acre of land people would rightly realise that it was much larger than average. However, they would not appreciate the size in the sense of knowing what a metre or a litre or a foot is.

Having been brought up with Ordnance Survey maps and the one kilometre-based National Grid it is easy to visualise hectares on maps. A hectare is a hundredth of an OS kilometre square. The central part of Trafalgar Square is roughly one hectare so a good reference point. I also like Martin’s example of an international rugby pitch.

An acre is based on an Anglo-Saxon strip field. I have never seen strip fields in this country so cannot accurately visualise it. It is a furlong by a chain and I have difficulty imagining what furlongs and chains are unless I convert into metres.

When looking into properties we should ask for plot areas in square metres or for larger ones in hectares. Strangely one place you will find hectares is in the property pages of Country Life where large properties are advertised.

Although I know that an acre is approx 4000 mÂ², when people say they want an acre of land, do they really know what that is, in terms of just how big it looks? I really cannot picture things in acres, although if it is 2.5 acres that is 1 hectare.

Hectare is a derived unit. The hect prefix means 100, and the unit is the “are” (pronounced like “air”). A bit of a strange word for area in English as it is the same word as “are” (from the verb “to be”, pronounced like “ahhr”).

So 1 hectare = 100 ares

1 are = 100 mÂ²

The “are” is not used much in English, if at all, probably because of its unusual spelling.

Hectare could be used as very few other metric units used today are used with the hect- prefix, although things like hectometre, meaning 100 metres, are valid for use in metric. Also loose food items are often priced per 100 g, but that could be written as per hectogram (hg).

The hectare is preferable to the acre, as it relates more closely to a unit length (i.e. the metre) whereas no one seems to know what an acre is in relation to any imperial unit.

Actually the hectare is equal to one square hectometre (hm^2). Since the unit are and none of the other prefixes are commonly used with the are (other then hecto), then I think the are as a unit along with any multiple/sub-multiple of it should be deprecated.

If one is expressing an area, it is best to just express it as A m x B m. This gives a better visualization of the lay of the land. One of the handy uses of square units is when pricing (currency unit per area). In that case, then the unit should be square metres or any prefix attached to square metres to put the numbers in the appropriate range.

The are and its prefixes, like the litre are not a part of SI and should not be promoted.

In many states of the USA a unit called ‘commercial acre’ may be used legally to sell land. It measures exactly 36 000 sq.ft compared to the statute acre of 43 560 sq.ft. It was invented by real estate agents and is supposed to be the portion of an acre after deduction of infrastructure. Legal con trick is a better expression. If you buy ’100 acres’ of land in one of these states, you may be in for a nasty surprise, 9.

In the Middle Ages most fields in Britain and in mainland Europe were long and narrow and the acre was also based on it: four rods by one furlong. The word acre, not the unit, has survived in the German and Dutch speaking parts of Europe: an ‘akker’ is a field for growing crops. A farmer may have, for instance, 100 ha ‘akkerland’. And, by the way, Trafalgar Square in London measures 1 hectare.

What is the problem with an acre?

1 acre = 4840 sq yds = 1 chain (22yds or the length of a cricket pitch) * 1 furlong (220yds or 1/8th of a mile).

A football pitch used to be about 1 acre in size, but that seems to have changed with metrication.

Jon Child really answers his own question. The actual dimensions of an acre are obscure and little known by the general public, and manipulating the data requires prodigious calculations (JC could have added that there are 640 acres in a square mile). Most people just know that an acre is a big piece of land, and that 6 acres are more than 5 acres. As a unit of measurement it is hopeless.

By contrast, as described in previous comments, 100 m X 100 m = 10 000 square metres (m2) = a hectare (ha), and 100 ha = a square kilometre (km2). Dead easy.

The size of a football pitch has not changed significantly for over a hundred years. For a first class match it is approximately 100 m x 70 m, or 7000 m2, whereas an acre is about 4000 m2.

I think the real problem affecting take-up of the (new-fangled) hectare is that most people really have a problem estimating 100m in length.

In my experience the guess tends to fall far short of 100m, in the 50-80m range, so their estimate of a hectare would therefore be about 1/3 to 2/3 the area of the real thing.

The rugby pitch size estimate (above) helps me – but they tend to look much smaller on TV than in reality

As a member of a Borough Planning Committee, all applications are measured in hectares, prior to being elected a hectare was an alien concept to me however, as a Rugby fan I can easily picture the area and mentally apply this to the applications. This was of real assistance.

As for Trafalger Square, I did know this, but not having been to London, (I do not often venture abroad) I could not picture the area. Living in Rural North West an acre is well known.

Who needs to visualise an area of land anyway? If you are a farmer or surveyor you will soon learn to do it, anyone else can look it up on Google and measure it, or use a GPS and pace round it.

We are buying a house in Portugal, and had to convert the stated area in square metres into acres in order to be able to compare its value with that of land in the UK, which everyone I know values by the acre. We were surprised to discover from our Brazilian friends that they use acres as well, and on investigation so do many other countries, including Portugal. Seems the British established the units as they surveyed the World and it stuck.

Why we are in such a mad rush to convert to metric units that are impossible to visualise when we had units of measurement that related to quantities we are familiar with in bodily scale I don’t know – I know exactly how big a 6ftx4ft window is, but in millimetres? Give me a break! And when it comes to pressure, forget it. The other huge benefit of non-metric units is that it teaches people to calculate in different bases than 10, so their maths becomes much better. It is only engineers that like everything to be so neat and tidy, to suit their obsessive temperement.

Wow. I grew up in Britain and the math I did was largely the 240 pennies to the pound kind. What nutter came up with that? Metric is far simpler and makes more sense … I can’t believe the number of people who are delighted to learn that a litre of water weighs a kilo, 500mL weights 500g, 125mL weighs 125g, etc.

Why all the silly chatter about sports fields? Is it a man thing? 100m x 100m is all I needed to know.

I think that JC has answered his own question!

1 Acre is 4840Sq Yds what sort of measurement is that? neither here nor there,

1 Chain??? what type of chain an Anchor chain, bicycle chain, 22yds, why not 20yds or 25 yds. and so forth.

I lived in the middle east for 36 years, from the age of 23 (born and raised in the UK) but the Metric System simplified life immensely.

Martin,

I don’t know if it is worth updating this old thread, but I was looking at how big is a baseball field, and would like to offer some observations/corrections:

*I agree the most common shape for fair territory is a square, with a corner lopped off as you have drawn. The range of dimensions is correct for “all parks,” but new parks, built after 1958 must have foul lines greater than 99 m and center field, 122 m. This shape and the minimum dimensions result in an area of 9483 m²

*The shape need not involve right angles at the foul posts. The true minimum shape is the straight lines connecting these dimensions, but approximating the arc to which these lines are chords results in a longer “power alley.” Thus the angle of the fence to foul line may be acute, right, or obtuse. This leads to about ±10% variation from shape, with no change in dimensions (but what you show is most common)

*Like the rugby field, there is some “extra territory” which should be considered. If an opposing player catches a foul fly, batter is out. A 60′ (18.3 m) swath of foul territory is recommended from first base to home plate, to third base. In the outfield, this can narrow to nearly the foul poles. Adding this brings the minimum field size to about 11860 m², and the maximum size area to about 13720 m².

Perhaps 1.2 – 1.4 ha would be a better statement. (And for a given foul line and center field dimension, 10% from shape is still possible).

For my own judgement of a hectare, I note that 6 lots in my subdivision taken together are just over 0.9 ha. It takes me 45 minutes to mow my lawn. Running back and forth on six such lots for an hour or two, playing a game, would surely kill me.

Was reading this and surely there’s an error on the calculations about football? 64 m x 100 m is 6,400 sq m ie 0.64 hectare, and 75 x 110 is 0.825 hectare

I thought a football field is always 100m by 50m.

Here’s my rough and ready way of working out how big a hectare is:

1 I walk briskly for one minute. In that time I will have walked about 100 metres. The square of that 100 metres is a hectare.

2 I count 125 steps at a brisk walking pace. The distance will be about 100 metres. The square of that 100 metres is a hectare.

3 As a check, I walk briskly for a minute, counting the number of steps. The count comes out between 120 and 130 steps. I got an equivalent reading (75 cm per step) when I set a pedometer.

In this way I can make rough calculations of areas.

Can you also put a picture of an Australian rules football ground?

If you look up “Hectare” in Wikipedia, you will see a “New Zealand Rules” rugby field.

All this about acres!

Surely we all know that an acre is the area one man can plough with a single ploughshare behind a horse or ox in one day. This makes it much easier to visualise!!!

The problem here is twofold. Firstly in the UK the pre-metric measurements come from antiquity and to the modern eye are not based on any sensible reasoning.

Secondly readers are from all over the world – and have little idea (in the same way anyone under the age of 45 in the UK) about anything pre-metric. Old timers like myself had to learn about not just acres and chains (chains are really useful for measuring land as they really are chains so they do not stretch or wear) but perches, rods, fathoms and all manner of other measurements.

However some of these old measurements do have a good foundation and are related to body measurements so one can approximate very easily.

The metric measurement system came into use in the UK in 1970, so the first thing I had to do when I started teaching was to throw away all the imperial rules and teach using the metric system. Within a couple of years I realised that transition would be much slower then anticipated so I included imperial measurements again alongside the metric ones. This was a good move because imperial measurements are still widely used, even if little understood.

I use metric measurements and imperial measurements – if I am making something I might use both on the same task choosing the one that seems most appropriate.

I pity very young children struggling with measuring in mm, the system is good but the actual distance is small. When Imperial was used small children could use quarter inches, then go to eighths then sixteenths, and thirty-seconds etc. as dexterity increases.

@Tony

This is a ridiculous assumption. A Ha is 100 m x 100 m pure and simple. Anyone in the world can visualise 100 x 100 be it metres or if you will even those other things 10% shorter, as an estimate 10% is withing D(a)fT regulations.

As a septaginairian I have no idea whatsoever as to how much a horse can plough in a day, even though I have seen them do it. How many of todays youth have never even seen a horse? Even I have never seen an Ox.

‘This was a good move because imperial measurements are still widely used, even if little understood.’

A good move? Another ridiculous statement of contradiction. Don’t you see yourself as part of the problem? It is the chicken and egg situation again.

So, explain why 50% of the world can change from post war Imperial to almost 100% metric within a few years and us in UK are regarded as so thick, stupid and ignorant that you assume we cannot cope.

The populace at large cannot progress to metric so long as the government and the media (and presumably the education sector) persist in using stupid meaningless units that MANY of us order folk find quite difficult too understand. I have often sat in class wondering ‘why don’t we use metric instead? That way I could understand.’ That was 60 years ago.

‘the system is good but the actual distance is small.’

This may be true if you are a carpenter. What if you are working with light or radio waves? Where is the inch then?

This is the universal problem with you people, you can always pick an isolated example out of a hat and say ‘This fits lets use it’. There is a much bigger world out there.

I could go on forever, I have detested Imperial from day one, and you, the non-teachers were the bane of my life. I learnt in the university of life.

A quick guess why cricket pitch is 20.1 m?

@ Alan Schweiser says:

2013-12-01 at 14:37

A quick guess why cricket pitch is 20.1 m?

A cricket pitch is (or was) 1 chain between the stumps. An acre is 1 chain by 1 furlong, there were 100 links of 7.92 inches to the chain and 10 chains to 1 furlong and 8 furlongs to the mile.

I hope that helps you. It never did much for me.

The question posed above is no doubt designed to make the point that a cricket pitch was defined historically in imperial units.

Well, alright, it is generally documented as 22 yd with a bracketed conversion (in varying degrees of precision) in metres. The exact figure is in fact 20.1182 m according to the modern definition of a yard (0.9144 m).

However, in practice, just how long are pitches in reality? Unlikely they are constructed to an accuracy of 0.1 mm. Some references quote 2012 cm. Even if we accept that they are constructed to within 1 cm where does that leave us?

2012 is not exactly a round number, but then neither is 22!

Doug Sheehan posted this illuminating comment on UKMA’s facebook page. It may interest readers of MV also.

“Listening to the Ashes on TMS, it warms my heart to think that cricket was one of the first sports to introduce a proto-metric measuring system.

The wicket is 20.12 metres long, not perhaps an obvious metric unit. This length, 20.12 metres, is of course the length of a Gunter’s chain. The chain was introduced in 1620 by Edmund Gunter to improve the measurement of agricultural land. There are those who claim the chain as imperial, but we must remember that the chain is made of links; each link is 201.2 mm, or 7 and 24/25 inches. Twenty-four twenty-fifths is an odd fraction even by the Byzantine standards of imperial. The Rev Gunter chose 201.2 mm because that would give his chain 100 links, a good proto-metric number.

But why 20.12 metres? Simply because one square chain is one tenth of an acre. So he divided an acre by ten to get a square chain, and divided the chain by 100 to get links (or centi-chains).

A measurement built on multiples of 10, a proto-metric system.

Cricket at its core is built on metric principles dating back to the reign of James VI of Scotland (James I of England), that’s about as traditionally British as you can get.”

An acre is simply 212 feet x 212 feet. Not all that complicated…………

@Slobo says:

2013-12-12 at 17:55

An acre is simply 212 feet x 212 feet. Not all that complicated…………

Really? I will have to get the linseed oil out and give my slide rule a rub down and check that out, but like the are, the acre does not square easily.

A standard acre is 1 chain by 1 furlong = 22 yards x 220 yards = 4840 square yards, x 9 = 43,560 square feet. The square root of 43,560 is 208.71032. So I recon an acre is 208.71032 ft x 208.71023 ft, not exactly simple to my simple old brain, metric wins for me every time!!!.

No, an acre is not 212 x 212 ft. That would be 44 944 ft² or 1.032 acre approx. An acre is 43560 ft². If you want a square, it is 208.710 325 571 113 ft approximately (66*sqrt(10)) on a side, an irrational number, so the decimals continue forever without repeating

.

If you want a nearly square rectangle with rational numbers, 198′ x 220′ is as close as you can come with integer feet, 206.25′ x 211.20′ to surveying accuracy (0.01 ft resolution).

The irrational number makes it fairly complicated. Now a hectare (10 000 m²) is a number that has a convenient, integer square root and is 100 m on a side.

thanks for the help i really needed it for a school project

I can not relate size to sports fields! What’s wrong with using both metric and U.S. measurement in both america. As it is with metric, many store especially grocers know that most older people are clueless, so they complicate matters by using one or the other on prices per lbs. or kg so no one is really sure what the “cost” is until they get to the til. Many of us are at the mercy of hoping for honesty which there is very little of in the business world. Consequently the government sees nothing wrong with helping their friends ( I mean crooks)! Buyer beware. My advice, if you’re not sure be it land or food, refuse to purchase. They’ll figure it out.

Ed, it’s easier to measure in the metric system and the worst thing of all is to have a mixture of measures. If you have different measures, it’s confusing – like acres and square miles, or acres and hectares. At least with acres and hectares, 10 acres is just over 4 hectares. However with acres to square miles there’s no easy rule of thumb. Ditto with ounces and pounds, with inches, feet, yards, furlongs and miles, and with fluid ounces, pints and gallons. That’s what’s wrong with the old measures and why they have been largely replaced by the metric system in most of the world.

@Ed

I agree with your sentiments on relating land area with sports fields, I have never seen one. Likewise swimming pools, footballs and golf balls, I really have no conceptual idea of their size. Double decker busses, well, that is something else.

However as for acres v hectares there can surely be no contest, 100 x 100 (metres or approximate yards) beats 22 x 220 (feet, or was that 1 chain x 1 furlong? or was it something in yards, or ploughing a field, ah yes! That was it! The seen everywhere horse and ox plough!!) any day of the year.

*** Once again I have to take exception to accusing us old folk of being stupid, this is another media hyped up non-fact that makes many old folk think there is some sort of difficulty in metric, and they need to fit into the stereotype. We may be a bit slower, but the subject, IF treated properly (ie not surrounded by some mystical complications of media stupidity) is realy quite simple and most of all logical and straightforward.

Interestingly, reading my post after posting, I did actually get feet and yards wrong.

Now that IS old age! I have forgotten those Imperial things already.

BrianAC,

Seeing you express the acre in yards (Americans think in feet) made a graphic pop into my head. Bear with me.

1) The acre of 22 yd x 220 yd is equally well expressed as 44 yd x 110 yd (not quite so long and skinny)

2) The approximation of 110 yd ~ 100 m is the basis of conversion for all track events in athletics, decades ago. 44 x 110 yd is nearly 40 x 100 m (40.2336 m x 100.584 m, with exact conversion).

3) In a scale drawing overlaid on the 100 m x 100 m hectare, this really helps visualize the acre as roughly 40% of a hectare (better than 1.2%), with some odd little bits hanging over.

The math works equally well with a 132′ x 330′ acre, but it didn’t smack me in the face.

I do one-to-one physics tutoring at “A” Level (16-18 year-old students). I have one student who get co0nfused between millimetres and centimetres, also between kilonewtons and meganewtons. This confusion is not due to old age, it is due to poor teaching, not necessarily in the schools, but by society at large and especially the tabloid newspapers who persist in converting everything back to imperial units.