Convert acres to ha acres ↔ hectares Free Online Secure
Type a value in acres and read it in hectares at once. The factor is exact by definition, the arithmetic happens in your browser, and nothing is sent anywhere.
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Common values — Convert acres to ha (acres ↔ hectares)
| ac | ha |
|---|---|
| 1 | 0.40468564224 |
| 2 | 0.80937128448 |
| 3 | 1.21405692672 |
| 5 | 2.0234282112 |
| 10 | 4.0468564224 |
| 20 | 8.0937128448 |
| 50 | 20.234282112 |
| 100 | 40.468564224 |
Where these units come from
Square units need no definition of their own: a square metre is a metre by a metre, and everything follows from the length. The land measures are older and stranger. The acre began as the land a yoke of oxen could plough in a day, which is why it was long and thin rather than square — one chain by one furlong, 4840 square yards. The hectare and the are came out of the French Revolution, when land had to be measured in something decimal; neither belongs to the International System, but both were kept for land because a hectare is a comfortable size to picture and a square metre is not. Since the 1959 agreement on the yard, the acre is exactly 4046.8564224 square metres, so the conversions on this page are exact rather than approximate.
Where you meet them
Square metres price flats, size carpets and decide how much paint a wall needs; square feet do the same work in the United States and in much of the property market worldwide. Hectares belong to farmland, forests and planning permissions; acres to land deeds in the English-speaking world. Square kilometres and square miles are for countries, lakes and fires. Square centimetres and square millimetres live in workshops, on datasheets and anywhere a cross-section matters.
Questions people ask
Is an acre the same in the United States?
For every practical purpose, yes. The international acre used here is exactly 4046.8564224 m². The United States also kept a survey acre, based on a slightly different foot, which was larger by about four parts in a million — a difference of some 160 cm² in an acre, invisible except in large land surveys. That survey foot was formally retired at the end of 2022, so only one acre is now in use.
How big is a hectare, really?
A hectare is a square of 100 m by 100 m, which is 10,000 square metres or about 2.47 acres. A full-size football pitch, touchline to touchline, is roughly 0.7 of a hectare, so a hectare is a pitch and a half. The are, now rarely used on its own, is a hundredth of that: 100 square metres, a square ten metres on a side.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
Why acres and hectares keep meeting on the same page
An acre is the land measure of the English-speaking farming world; a hectare is the measure of nearly everyone else. A British auction catalogue lists a paddock as 12 acres, a Romanian buyer thinks in hectares, and the EU subsidy form asks for hectares only. To convert acres to ha you multiply by 0.4047, which is a small step, but the answer has to be right because land is sold by the unit and a one per cent mistake on a large farm is a lot of money. This page does the multiplication as you type and then spends the rest of its length on what the two units mean.
Below you will find the rule with worked examples, short profiles of both units, a comparison, a tour of real situations from farms and parks to solar fields, and a list of the errors people make most often. If you only need the number, the converter above has it; if you need to trust the number, read on.
How to convert acres to ha: multiply by 0.4047
The rule
One acre is 0.40468564 hectares. To convert acres to ha, multiply the acres by 0.4047. Ten acres are 4.05 ha, a hundred acres are 40.47 ha, and one acre alone is a little over four tenths of a hectare. Going back, one hectare is 2.471 acres, so divide by 0.4047 or multiply by 2.471.
Worked examples
A 25 acre field is 25 times 0.4047, or 10.12 ha. A smallholding of 3.5 acres is 1.42 ha. A ranch of 640 acres, exactly one square mile, is 259 ha. When you only need a rough answer, take 40 per cent and add a little: 50 acres is about 20 ha, and the exact figure is 20.2.
Fractions of an acre
Half an acre is 0.2023 ha, a quarter of an acre 0.1012 ha, and a tenth of an acre 0.0405 ha, which is 405 square metres. House plots are often quoted this way, so remember that a quarter acre is just over a tenth of a hectare.
A quick check
The hectare is the bigger unit, so the number of hectares must be smaller than the number of acres. If a “convert acres to ha” calculation gave you a larger number, you divided instead of multiplying.
The acre
A furlong by a chain
The acre is 43,560 square feet, or 4,046.86 square metres. Medieval farmers defined it as the area one man with a yoke of oxen could plough in a day, later fixed as a strip one furlong long and one chain wide, that is 660 by 66 feet. A square acre would measure about 63.6 metres on each side.
Where it is used
The acre is the working unit for land in the United States, the United Kingdom and Ireland, and in parts of Canada, Australia and India. Farms, building plots, parks and golf courses are all described in acres.
The hectare
Ten thousand square metres
The hectare is a square of 100 metres by 100 metres, 10,000 square metres, or 2.471 acres. The name was coined in revolutionary France in 1795 from hecto, a hundred, and are, the old unit of 100 square metres. It was meant to give farmers a number that fitted the decimal metric system.
Where it is used
Hectares measure farmland, forests and nature reserves across Europe, Africa, Asia and Latin America, and they are the unit in international statistics and in the European farm subsidy system. Even English-speaking scientists write in hectares.
Acre and hectare compared
A hectare holds almost two and a half acres, so the acre is the finer unit and the hectare the coarser. A garden fits easily in acres, a district in hectares. Because the relation is not a round number, the two scales rarely line up, and anyone who works between countries should convert before comparing prices or yields.
The difference also matters for yields. A wheat crop of 3 tonnes per hectare is 1.2 tonnes per acre, and a price of 5,000 euros per hectare is only 2,023 euros per acre. A buyer who forgets this will think a field is cheap when it is not.
Where the conversion appears
Farms and fields
The average American farm has about 463 acres, which is 187 ha. The average farm in the European Union has about 17 ha, or 42 acres, and in Romania only about 3 ha, or 7.4 acres. Statistics offices publish in their own units, so a comparison between countries starts with a “convert acres to ha” calculation.
Parks and gardens
New York's Central Park covers about 843 acres, or 341 ha. London's Hyde Park has about 350 acres, 142 ha. Visitors reading guidebooks from one country while standing in another meet both numbers within a day.
Property listings
A rural listing may say 10 acres, which is 4.05 ha. A forest lot of 40 acres is 16.2 ha. Agents usually give both, but when they do not, divide by 2.47 or multiply by 0.4047 to find the second figure.
Vineyards and orchards
A hectare of vines holds 4,000 to 5,000 plants, so an acre holds 1,600 to 2,000. Wine estates in California quote acres, estates in Europe hectares. An estate of 120 acres has 48.6 ha, and at 5,000 vines per hectare that is about 243,000 plants. Planting density, labour hours and yield per hectare are all calculated per unit of land, so use the same unit for all three.
Forests and timber
Foresters speak of cubic metres per hectare, while American forestry uses board feet per acre. A stand of 30 acres is 12.1 ha, and if each hectare gives 250 cubic metres, the whole yields about 3,000. Both units appear in the same contract when a European buyer purchases timber from an American seller.
Urban sprawl and housing density
Planners measure housing density as homes per acre or per hectare. Ten homes per acre is 24.7 homes per hectare, and four homes per hectare is 1.6 per acre. When a city compares itself to a foreign one, the first step is a “convert acres to ha” calculation on the density figures.
Airports and large sites
Airports, factories and campuses are often described by area. A campus of 200 acres is 81 ha, which is the area of 113 football pitches. The unit used on the site depends on the owner, but the reader still wants a single scale.
Teaching the conversion
In a classroom, give each group a rope 63.6 metres long to mark a square: that is one acre. Then ask them to mark a square 100 metres on a side and compare. Students see that the hectare is a little more than two and a half times as large, and the number 0.4047 stops being abstract.
Water, irrigation and rainfall
Irrigation is measured as depth over area: one inch of water on one acre is about 102.8 cubic metres, and 25.4 mm on one hectare is 254 cubic metres. A farmer converting between systems has to convert acres to ha and also convert depth, otherwise the volumes will not match.
Reading a land register
A land register or cadastre records each parcel with its area and its owner. In Romania and most of Europe the area is written in square metres or hectares, often as 2.4567 ha with four decimals. In Britain and the United States deeds give acres, roods and perches, or decimal acres. If you hold an old deed and want to convert acres to ha, check first whether it uses decimal acres or the older roods and perches, because 4 roods make an acre and 40 perches make a rood.
Pasture and livestock
Stocking rates link animals to land. A farm may keep 2 cows per hectare, which is 0.8 cows per acre, or 5 sheep per acre, which is 12.4 per hectare. Extension services in different countries publish tables in their own units, and a farmer who reads a foreign guide has to convert the density, not only the area, to get a sensible number.
Cemeteries, campuses and fairgrounds
Large public sites are often compared by size. A university campus of 300 acres is 121 ha, a fairground of 50 acres is 20.2 ha and a cemetery of 15 acres is 6.1 ha. These numbers are easy to picture when you compare them with a known place, and the comparison is easier in hectares for a European reader and in acres for an American one.
Mining, quarries and landfill
Permits for quarries and landfill sites list the area that may be disturbed, in acres in North America and hectares in most other countries. A quarry permit for 80 acres allows 32.4 ha. Environmental reports often convert between the two so that regulators from different countries can read the same document.
Wildfires and floods
News reports measure wildfires in acres in the United States and in hectares in Europe and Australia. A fire that burns 100,000 acres has destroyed 40,469 ha, which is about 405 square kilometres. A reader comparing a Californian fire with a Greek one needs a “convert acres to ha” calculation to see which was larger.
The Homestead Act
In 1862 the United States offered 160 acres, 64.7 ha, to anyone who would settle and farm it for five years. The phrase "forty acres and a mule" refers to 40 acres, 16.2 ha. These figures show how the acre became a political unit as well as a measure: a quarter section, 160 acres, was the size of a family farm for generations.
Allotments and community gardens
An allotment plot in Britain is traditionally 10 rods, about 250 square metres, which is 0.0618 acres or 0.025 ha. A community garden of one acre has 16 such plots. Gardeners who share seed catalogues from different countries should note that sowing rates are given per square metre, per acre or per hectare depending on the seller.
Fertiliser and seed rates
Fertiliser is applied in kilograms per hectare in most of the world and in pounds per acre in North America. A dose of 100 pounds per acre equals 112 kilograms per hectare. When you read a recipe from a foreign guide, convert both the mass and the area, or the dose will be off by a factor of two or more. A “convert acres to ha” calculation alone is not enough.
Why the acre survives
The acre is old, convenient and tied to legal records. Changing it would mean rewriting deeds, maps and loan contracts, and few governments want to. Meanwhile the hectare is the unit of science and of international trade. The result is that both stay in use, and a small tool that converts between them saves time in every office where land is bought, sold or measured.
Irish and Scottish acres
Before the nineteenth century, Ireland used an acre of about 1.62 statute acres, 0.655 ha, and Scotland one of about 1.27 statute acres, 0.514 ha. Old maps and deeds that mention an Irish acre therefore describe a larger plot than a modern acre. If you are researching family land records, check which acre the document meant before you convert acres to ha.
Solar fields
Large solar parks need roughly 5 to 10 acres per megawatt, or 2 to 4 ha. A 50 MW plant may therefore cover 250 to 500 acres, which is 100 to 200 ha. Developers in the United States talk about acres, planning authorities in Europe about hectares, and the two documents have to agree on the same land.
Golf courses
A typical 18 hole course occupies 120 to 200 acres, which is 49 to 81 ha. A links course by the sea may have less land than a parkland course because the fairways wrap around the dunes. Developers quote acres in the United States and hectares elsewhere, so a proposal for a resort abroad may describe the same plot in both.
Football pitches as a yardstick
A standard football pitch of 105 by 68 metres covers 7,140 square metres, which is 0.714 ha or 1.76 acres. A field of 10 acres is therefore about 5.7 pitches, and 10 ha is about 14. Journalists use pitches to make large areas understandable, and the comparison works in either unit.
Rounding for land prices
Land sells for a price per unit, and a small rounding error becomes a large sum. At 8,000 euros per hectare, an error of 0.01 ha is 80 euros. Keep four digits in your factor, 0.4047, and round only the final answer. For legal documents, use the exact factor 0.40468564 and the number of decimals your register requires.
Spreadsheet use
In a spreadsheet, put acres in column A and write =A2*0.40468564 in column B. To go the other way use =A2/0.40468564. Format the answer with two decimals for hectares. If you are building a sheet for a farm with many parcels, add a total row so you can compare it with your title deeds.
A hectare in everyday terms
A hectare is a square of 100 metres on a side, about the size of a city block or one and a half football pitches. An acre is a square of about 64 metres, the size of a small park or of two house plots with gardens. These pictures help you check an answer by eye.
More values for convert acres to ha
A longer list of conversions
If the value you need is not in the first list, these further conversions may be close enough to read off directly:
- 0.1 ac = 0.040468564224 ha
- 0.5 ac = 0.20234282112 ha
- 3 ac = 1.21405692672 ha
- 4 ac = 1.61874256896 ha
- 7 ac = 2.83279949568 ha
- 15 ac = 6.0702846336 ha
- 20 ac = 8.0937128448 ha
- 75 ac = 30.351423168 ha
- 200 ac = 80.937128448 ha
- 500 ac = 202.34282112 ha
- 2,000 ac = 809.37128448 ha
- 10,000 ac = 4,046.8564224 ha
Mistakes when you convert acres to ha
Dividing instead of multiplying
One acre is smaller than one hectare, so the number gets smaller. If 10 acres turned into 24.7, you used the wrong direction.
Mixing up the square mile
A square mile is 640 acres, 259 ha, not 100 ha. Do not confuse miles and acres in the same sentence.
Using the wrong acre
Old Irish and Scottish documents use different acres. Check the source before you convert.
Quick answers
How many hectares in an acre?
0.4047.
How do I convert acres to ha?
Multiply by 0.4047.
How many acres in a hectare?
About 2.471.
What is 100 acres in hectares?
40.47 ha.
Does my number leave my device?
No. The calculation runs in your browser.
Related pages and a last word
If you work with land and area, these conversions are close at hand: Convert acres to ft², Convert acres to mi², Convert m² to ha, Convert km² to ha, Convert ha to m², Convert km to mi, Convert mi to km, Convert °C to °F, Convert °F to °C. The reverse of this page is Convert ha to acres.
In short, to convert acres to ha multiply by 0.4047, remember that a hectare is 10,000 square metres, and keep four digits until the final answer. Your number stays on your device: nothing is uploaded and no account is needed.