What this calculator does
Find out how many hectares a piece of land is, or how many acres. Acres and hectares are the two units people use to measure land, like farms, woods, parks, building lots and estates. The acre is the traditional unit in the United States. It's still common in property listings in the UK, Canada and Australia. The hectare is the metric land unit. Most of the world uses it for land records, crop figures and planning papers.
A hectare is a square 100 meters on each side, so it's exactly 10,000 square meters. The international acre (the standard acre today) is set at exactly 43,560 square feet. A foot is exactly 0.3048 m. So one acre is exactly 4,046.8564224 m², or 0.40468564224 hectares. This page converts either way with that exact number.
Where it's used
Why this math matters outside the classroom:
- Farmland listings. A 160 acre farm is about 64.7 hectares, the unit used in land records in most countries.
- International reports. Researchers convert crop areas reported in hectares to acres for US readers by multiplying by about 2.471.
- Parks and campuses. City planners describe a 50 hectare park as about 123.6 acres for US residents.
- Forestry maps. Foresters convert stand sizes between hectares and acres when working with maps from different countries.
- Squared units. Students see that a hectare is a 100 × 100 m square, which is 10,000 m².
Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 6.RP.A.3.d. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Enter the land area. Parts of an acre or hectare, such as 0.75, are fine.
- Pick the direction: acres to hectares, or hectares to acres.
- Read the result and the working. The table lists common land sizes in the direction you chose.
What the inputs mean
- Value to convert
- An area in acres (for ac → ha) or hectares (for ha → ac).
- Direction
- Which way to convert. The reference table follows the same direction.
Formula and method
ha = ac × 0.40468564224 ac = ha ÷ 0.40468564224 ≈ ha × 2.47105381467
Here, ac stands for acres and ha for hectares. To go from acres to hectares, multiply by 0.40468564224. That number is exact.
It comes from three facts. An acre is 43,560 ft². Each square foot is 0.09290304 m². And a hectare is 10,000 m². So 43,560 × 0.09290304 ÷ 10,000 gives the factor.
Going the other way, there are about 2.471 acres in a hectare. That decimal never ends. So the calculator divides by the exact number instead of multiplying by a rounded one.
Worked example
A listing describes a 10-acre property. How many hectares is it?
- The factor is exact: 1 ac = 0.40468564224 ha.
- 10 × 0.40468564224 = 4.0468564224.
Result: 10 acres is 4.0468564224 ha, a little over 4 hectares.
Understanding the result
Here's a quick way to estimate in your head. Multiply acres by 0.4 to get hectares; the answer comes out about 1.2% low. Going the other way, multiply hectares by 2.5; that comes out about 1.2% high. For 10 acres, the shortcut gives 4 ha, against the exact 4.05 ha.
Some handy reference points: one square mile (640 acres, a "section" in US land surveys) is 258.999 ha, just under 259 ha. A quarter section of 160 acres is about 64.75 ha. One square kilometer is 100 ha, about 247.1 acres.
To picture a hectare, think of a square 100 m by 100 m. An acre fits inside it about two and a half times.
Assumptions and limitations
- The acre is the international acre of 43,560 international square feet (4,046.8564224 m²).
- The hectare is exactly 10,000 m².
- Older US land records may use the US survey acre. It's based on the survey foot, which was retired at the end of 2022. It's about 4 parts per million larger. That matters only for very large parcels or exact legal descriptions.
- Old regional acres (such as the old Scottish or Irish acres) were different sizes and aren't covered.
Frequently asked questions
How many acres are in a hectare?
About 2.47105381467 acres. It's 1 divided by 0.40468564224, so the decimal never ends.
Is a hectare bigger than an acre?
Yes. A hectare is roughly two and a half times the area of an acre. So a land size in hectares is always the smaller number.
What is the difference between the international acre and the US survey acre?
The survey acre was based on the US survey foot (1200/3937 m) instead of the international foot (0.3048 m). It works out to about 4,046.8726 m², roughly 0.016 m² more per acre. New US work uses the international foot.
Why is the hectare called a hectare?
"Hecto" means 100, so a hectare is 100 ares. An are is 100 m². The are itself is rarely used today, except in a few countries' property records.
How this calculator is checked
Method: International acre = 43,560 ft² with 1 ft = 0.3048 m (1959 agreement), so 1 ac = 4,046.8564224 m²; 1 ha = 10,000 m². The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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