Hectares vs. Acres: Which Countries Use Which?

Farmland in France is quoted in hectares. A lot in Texas is quoted in acres.

The jurisdiction settles the unit, not the person reading the listing, and since the two differ by a factor of roughly two and a half, knowing which is which avoids the more expensive kind of misunderstanding.

Countries fall into three groups, and the third is the interesting one: those that measure land in hectares, the handful that stay with acres, and the sizeable middle that registers land in one unit while talking in the other.

The world runs on hectares

The hectare is the standard land unit in the overwhelming majority of countries. Every member state of the European Union uses it. So do India, China, Brazil, Australia, New Zealand, Japan, South Africa and essentially all of Africa, Asia and South America. When land area appears in a national statistical release, a planning document or a land registry entry, the hectare is the near-universal choice.

The uniformity exists because the hectare travels with the metric system, and the metric system is now effectively global. The United States, Liberia and Myanmar are the three countries usually named as never having mandated metric units for everyday domestic use — a useful rule of thumb, though a loose one, since the United States has defined its customary units in metric terms since 1893 and named metric its preferred system in 1975. Everywhere else, adopting SI meant adopting the hectare for land, whatever was in use beforehand.

International bodies follow suit. The Food and Agriculture Organization reports crop areas, forest cover and land use in hectares for every country it covers, including the United States. Anyone comparing agricultural data across borders is working in hectares whether or not their own country does.

Which countries still use acres?

The United States is the significant exception. Acres run through American property and agriculture: deeds, plats, listings, county records, farm programmes and federal agricultural statistics are all in acres. Smaller urban lots are usually quoted in square feet instead, at 43,560 square feet to the acre, and very large rural holdings are sometimes described in sections, a section being one square mile or 640 acres.

This is not a preference a listing agent might vary. The American land record itself is built on acres. The survey grid that divided much of the country into townships and sections produced parcels sized in acres, and those descriptions still govern title today. Converting the record to hectares would mean rewriting it.

Myanmar and Liberia are the other two countries in that group. Both are far smaller cases, and Myanmar has announced its intention to move to metric units, so neither shapes international practice the way the United States does.

Which countries use both hectares and acres?

A third group is more interesting than either extreme, because the official answer and the everyday answer are different.

The United Kingdom is the clearest case. The hectare is the official unit: HM Land Registry records areas in hectares, agricultural payments are calculated per hectare, and planning documents use hectares as standard. Outside those systems, almost nobody talks in hectares. Farms are described in acres, rural property advertisements quote acres, and a great many listings give both figures with the acre first.

Ireland works much the same way. Land is registered and administered in hectares and farm support schemes are calculated on hectares, but conversation and much of the farming press stay with acres.

Canada metricated in the 1970s, and hectares are standard in government statistics and modern land data. Legal descriptions are more mixed: across Alberta, Saskatchewan and Manitoba, titles still run on the Dominion Land Survey grid of 640-acre sections and 160-acre quarter-sections, so an acre figure remains the authoritative identifier on many certificates of title. Rural real estate follows the same habit — acreage is the ordinary way to describe a country property, and residential lots are commonly given in square feet.

India uses hectares for government statistics and agricultural policy, acres very widely in practice, and a long list of regional units that remain in daily use alongside both.

Country-by-country reference

The United States entry deserves a footnote. Metric units are legally the preferred system for American trade and commerce, and American customary units are themselves defined in metric terms. None of that has reached the land record, which remains entirely in acres.

Why don’t hectares and acres line up?

The acre came out of farming. It described the area a yoke of oxen could plough in a day, and its dimensions came from how ploughing was organised: one furlong long by one chain wide, because long furrows meant fewer turns. Nobody designed it. It accumulated, and was tidied up by statute long afterwards.

The hectare came out of a commission. The metric system was created in France in 1795 with the explicit aim of replacing a chaotic mass of local measures with one rational scheme built on decimal steps. The are was defined as 100 square metres, and the hectare — "hect-" meaning a hundred — as a hundred ares, or 10,000 square metres. It exists because a square 100 metres on a side is a convenient size for a field and a round number in the system.

The two therefore sit together awkwardly. There was never any reason for them to align, and they do not.

How the metric system travelled

Metric units did not spread because the arithmetic is easier, although it is. They spread because a sequence of events made adopting them the path of least resistance.

1. Revolution and conquest. France carried the metric system into the territories it occupied under Napoleon, and much of continental Europe kept it after the occupation ended, because by then it had already displaced the local measures.
2. Trade. The Metre Convention of 1875 established international standards and a permanent body to maintain them. Signing was cheap, and staying outside made exporting harder.
3. Science. The scientific community standardised on metric units well before governments did, and technical education followed.
4. Reform and independence. Countries reorganising their institutions — after independence, after war, after a change of regime — routinely took the opportunity to adopt metric units at the same time.
5. SI itself. The International System of Units, established in 1960, gave the metric system a single coherent definition and a standing organisation behind it, which made partial or idiosyncratic versions harder to defend.

Was the metric system resisted?

The system had a rough start at home. It was unpopular enough in France that a hybrid of old and new measures was permitted for a generation, and metric units only became compulsory there decades after their invention. That is worth remembering when the persistence of the acre is treated as peculiar: resistance to new measures is the normal case, not the exception.

By the second half of the twentieth century, adopting metric had become the default for any country modernising its administration. The hectare came along with everything else, because a metric land unit was simply what the system provided.

Empire, independence and the units that came with them

The map of land units is largely a map of nineteenth-century influence.

Where French, Spanish, Portuguese, Dutch or Belgian administration reached, metric units generally followed and the hectare with them. Spain and Portugal adopted metric measures during the nineteenth century, and the newly independent republics of Latin America did the same, which is why the hectare is universal across the region today.

Where British administration reached, the acre came with it — to North America, the Caribbean, southern and eastern Africa, South Asia, Australia and New Zealand. But the acre did not stay. Most of those countries metricated between the 1950s and the 1970s, usually as a deliberate act of administrative modernisation, and their land registries moved to hectares along with everything else.

The result is that the acre is now less a British unit than an American one. Britain exported it, then dropped it from official use. The United States built its property system around it.

Why Britain only went halfway

The United Kingdom began metricating from the mid-1960s, when the government backed an industry-led programme to convert. Joining the European Economic Community in 1973 added further momentum, and that is how the hectare became the official land unit.

What did not change was the way people talk. British metrication proceeded sector by sector rather than by a single cutover, so the areas where the state has direct leverage — registration, subsidy, trade — converted, and ordinary usage did not.

This is not simple obstinacy. A farmer whose family has worked the same fields for generations knows those fields as acres, and the acre happens to be a convenient size for describing a single field in a way the hectare is not. The unit that survives in conversation is usually the one that fits the object being described.

Why has the United States never switched?

The United States has never been hostile to metric units in principle. It was among the original signatories of the Metre Convention in 1875, and since the Mendenhall Order of 1893 its customary units have been legally defined in terms of metric standards. The American acre is defined by way of the metre, whether or not anyone thinks of it that way.

The Metric Conversion Act of 1975 declared metric the preferred system for American trade and commerce but made conversion voluntary. Voluntary conversion does not happen in a market where nobody gains by moving first, and the board created to encourage it was wound up within a few years. Metric units took firm hold in American science, medicine and much of manufacturing, and made almost no impression on everyday measures.

Land was the hardest case of all, for the reason given earlier: the survey grid and the deeds that refer to it are written in acres, and restating them in units that do not divide the grid cleanly would buy nothing while the grid itself remained in miles.

Why do land units change so slowly?

Several countries metricated everything else and still kept acres in conversation about land. There are structural reasons for it.

• Records are permanent. A deed written in acres stays in force indefinitely. Changing the unit does not move the boundary, so the conversion buys nothing and costs a great deal of clerical work.
• Boundaries are physical. Fields, hedges, fences and roads were laid out in the old units and cannot be re-laid. A four-acre field remains a four-acre field however it is described.
• Land changes hands rarely. Units used daily — currency, fuel, groceries — convert quickly because everyone re-learns them within weeks. Most people buy land once or twice in a lifetime, so there is no repetition to drive the new habit in.
• The old unit is often the right size. An acre suits a field and a hectare suits a farm block. Where a traditional unit matches the thing being described, it tends to survive.
• There is no penalty for using both. Quoting acres and hectares side by side costs nothing, so the pressure to settle on one never becomes acute.

None of this is a judgement about which unit is better. The metric system is easier to compute with, and 100 hectares to the square kilometre is plainly tidier than 640 acres to the square mile. But land measurement is not really an arithmetic problem. It is a records problem, and records are conservative by design.

The sector matters as much as the country

Within a single country the unit often changes with the context. Sector conventions are frequently a better predictor than nationality.

Three things determine which unit appears on a given document, in roughly this order: the legal system that issued it, the sector it belongs to, and the audience it was written for. A French registry entry is in hectares because French law requires it. An American crop yield is per acre because that is what the American agricultural system reports. An Irish rural listing quotes acres because that is what the buyer thinks in.

Which unit does each sector use?

• Agriculture and forestry — hectares almost everywhere, because yields, stocking rates and subsidy payments are calculated per hectare and need to be comparable. The United States is the exception, reporting yields per acre.
• Environmental and conservation reporting — hectares universally, including for American sites when the figures appear in international datasets.
• Residential property — the most local of all. Square feet in the United States and Canada, square metres across most of Europe and Asia, acres for anything with land attached in Britain and Ireland.
• Commercial and development land — hectares in metric countries, acres in the United States, with very large sites sometimes described in square kilometres or square miles instead.
• Mapping and survey — square kilometres for large areas everywhere, at 100 hectares to the square kilometre and 640 acres to the square mile.

This is why a single country can produce documents in three different units on the same day. A British farm might appear as 48 hectares in a subsidy claim, 118 acres in the sale particulars, and 480,000 square metres in an environmental appraisal, all describing the same ground.

Local units that sit alongside both

In several large countries, hectares and acres are not the whole story. Traditional units remain in active use for buying and selling, even where official statistics have long since standardised.

India has the widest range. The bigha is used across much of the north but has no single value — it differs from state to state and sometimes from district to district. The guntha, common in Maharashtra and Karnataka, is a fortieth of an acre. The cent, used in the south, is a hundredth of an acre. Kanal and marla are used in the north-west. Land dealings routinely quote a local unit and an acre or hectare figure together.

China uses the mu alongside the hectare. It is fixed at one fifteenth of a hectare, so fifteen mu make a hectare, and farm sizes and land contracts are commonly stated in mu even where official statistics use hectares. Japan keeps the tsubo, roughly the area of two tatami mats, for building plots. Brazil has the alqueire, a rural unit whose value varies by region.

How do you read a land listing from another country?

1. Check the unit before the number. "5 ha" and "5 acres" differ by a factor of about two and a half, and a hurried reading of a foreign listing is exactly where that gets missed.
2. Treat the official record as authoritative. In metric countries the registry figure will be in hectares even when the advertisement quotes acres, and the registry figure is the one that appears in a contract.
3. Expect rounding in marketing material. A property described as about 10 acres may be 9.6 in the deed. Convert from the recorded figure, not the advertised one.
4. Watch for local units, particularly in India, China and parts of South America, and check the conversion locally.
5. Convert once and keep the full factor. Rounding a hectare to 2.5 acres is fine for conversation and not for anything you sign.

Hectares are the international default and cover almost every country. Acres are the American standard and the British and Irish habit. Where both appear on the same property, the registry decides which one is operative — and whichever it turns out to be, one hectare is 2.47105 acres.