How big is a hectare?
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 – 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. They only specify the length of the cricket pitch (20.12 m) – they do 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 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]
November 17th, 2007 at 16:34
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 10 000 square metres 1 hectare
100 m x 50 m 5 000 square metres ½ hectare
100 m x 25 m 2 500 square metres ¼ hectare
50 m x 50 m 2 500 square metres ¼ 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 www.simetricmatters.com
November 18th, 2007 at 06:43
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.
November 21st, 2007 at 11:54
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!
November 21st, 2007 at 22:15
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.
November 22nd, 2007 at 17:25
Although I know that an acre is approx 4000 m², 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 m²
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.
November 23rd, 2007 at 17:02
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.
December 7th, 2007 at 10:54
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.
May 8th, 2008 at 15:41
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.
May 9th, 2008 at 09:01
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.
August 15th, 2008 at 10:14
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
August 26th, 2008 at 08:36
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.
October 14th, 2008 at 05:25
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.