Acres to Hectares Converter
Convert acres to hectares for US land, farming, and international property comparison.
How It Works
Formula: acre to ha = value × 0.404685642
Example: 1 acre = 0.404686 ha
Note: 1 acre equals 0.4047 hectares, the US land unit converted to the metric area standard.
Common Uses
Quick Conversion Table
| acre | ha |
|---|---|
| 10 | 4.0469 |
| 50 | 20.2343 |
| 100 | 40.4686 |
| 500 | 202.3428 |
| 1000 | 404.6856 |
| 2000 | 809.3713 |
Rounding Rule
Rounded to 4 decimal places
Error Margin
±0.0001 ha
Precision Guidance
For land, round to 2 decimals. For farming records, keep 3-4 decimals.
Common Mistakes
An acre (0.405 ha) is less than half a hectare. Do not treat them as roughly equal.
Frequently Asked Questions
What is 1 acre in hectares?
1 acre equals 0.4047 hectares (1 acre = 43,560 sq ft = 0.404686 ha).
How do I convert acres to hectares?
Multiply the acre value by 0.4047. For example, 10 acres × 0.4047 = 4.047 ha.
How big is a hectare?
1 hectare equals 10,000 square meters, or about 2.471 acres.
Is this used for farming?
Yes, US farmland uses acres, while international agriculture uses hectares.
Deep Dive Guide
Acres to Hectares: Exact Land Conversion for US Farms and Large Lots
Convert acres to hectares accurately for US farmland, rural property, and international land comparison using the exact acre to hectare factor.
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Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 acre = 4046.8564224 square metres (exact, 43,560 ft²)
- EXACT1 hectare (ha) = 10,000 square metres (definition)
- EXACT1 square foot (ft²) = 0.09290304 m² (exact)
- EXACT1 square mile = 2.589988110336 km² (exact)
Common Pitfalls & How to Avoid Them
Acre is not a square
An acre is 43,560 ft² of area in any shape — it can be long and thin. One acre = 4046.86 m² = 0.404686 hectare.
Section vs. hectare
A US "section" is 1 square mile = 259 ha. A hectare (10,000 m²) is ~2.47 acres. Keep the two apart when reading land listings.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This converter was reviewed for accuracy