Quick Answer: Acres to Hectares
One acre is approximately 0.4047 hectares (1 ac ≈ 0.4047 ha).
Conversely, 1 ha ≈ 2.471 ac.
Formula: ha = ac × 0.40468564224
Worked examples
- 1 ac ≈ 0.4047 ha
- 2 ac ≈ 0.8094 ha
- 5 ac ≈ 2.023 ha
Method and limitations
Multiply acres by 0.40468564224. The international acre is 43,560 ft² = 4,046.8564224 m² exactly, and a hectare is 10,000 m², so 1 ac = 0.40468564224 ha. Calculations use full-precision constants; answers in this box are rounded for readability (≈ marks a rounded value) and the calculator shows up to 9 significant figures.
Each factor is exact by definition, derived from exact definitions, or a documented conventional value — see the methodology and sources.
Conversion Formula
Multiply acres by 0.40468564224. The international acre is 43,560 ft² = 4,046.8564224 m² exactly, and a hectare is 10,000 m², so 1 ac = 0.40468564224 ha.
Complete Guide to Acres to Hectares Conversion
What is an acre?
The acre (ac) is a land-area unit of 43,560 square feet, exactly 4,046.8564224 m².
What is a hectare?
The hectare (ha) is 10,000 m² (a square 100 m on each side), accepted for use with the SI.
How the Conversion Works
ha = ac × 0.40468564224, exact from the international foot.
Step-by-Step Conversion Guide
Follow these steps to convert acres to hectares manually:
Start with your value in acres
Example: You want to convert 5 ac
Apply the conversion formula
Use the formula: ha = ac × 0.40468564224
Calculate the result
5 ac = 2.0234 ha
Verify your answer
Use our calculator above to double-check your manual calculation.
Quick Mental Math Tip
Multiply by 0.4: 25 ac ≈ 10 ha (exact 10.12). Going the other way, 1 ha ≈ 2.47 ac.
Common Conversions
| Acres (ac) | Hectares (ha) | Hectares → Acres |
|---|---|---|
| 1 ac | 0.404686 | 1 ha = 2.47105 ac |
| 2 ac | 0.809371 | 2 ha = 4.94211 ac |
| 5 ac | 2.02343 | 5 ha = 12.3553 ac |
| 10 ac | 4.04686 | 10 ha = 24.7105 ac |
| 20 ac | 8.09371 | 20 ha = 49.4211 ac |
| 50 ac | 20.2343 | 50 ha = 123.553 ac |
| 100 ac | 40.4686 | 100 ha = 247.105 ac |
| 500 ac | 202.343 | 500 ha = 1,235.53 ac |
| 1000 ac | 404.686 | 1000 ha = 2,471.05 ac |
| 5000 ac | 2,023.43 | 5000 ha = 12,355.3 ac |
Did You Know?
Area conversions are non-linear: doubling the length of each side of a square quadruples its area, which is why area unit ratios are always squared.
Popular Acres to Hectares Conversions
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When You'll Need This Conversion
Land and property listings
Express a 5-acre plot as 2.023 ha for a metric listing or plan.
Site areas
A 640-acre square mile is 258.999 ha.
Common Mistakes to Avoid
Treating an acre as a fixed shape
An acre is an area, not a length; it can be any shape.
Convert the area, not a side length.
Frequently Asked Questions
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Conversion factors on this page are either exact by definition, derived from exact definitions, or conventional values in documented use. Each is listed with its source in our conversion methodology and sources, which cites the BIPM SI Brochure, NIST Special Publication 811 and the relevant IEC or national standards. Results are rounded for display only; calculations use full precision.