Quick Answer: Acres to Hectares
One acre equals 0.404685642 hectares (1 ac = 0.404685642 ha).
Conversely, 1 ha = 2.47105381 ac.
Formula: ha = ac × 0.40468564224
Worked examples
- 1 ac = 0.404685642 ha
- 2 ac = 0.809371284 ha
- 5 ac = 2.02342821 ha
Method and limitations
To convert acres to hectares, multiply the acre value by 0.40468564224. One acre is approximately 0.4 hectares. Calculations use full-precision constants; displayed values are rounded to at most 9 significant figures. Results are rounded for display only. Full precision is kept internally, so long chains of conversions do not accumulate rounding error. Where US customary and imperial units share a name (for example fluid ounces and gallons), this page uses the US customary definition and says so explicitly.
Each factor is exact by definition, derived from exact definitions, or a documented conventional value — see the methodology and sources.
Conversion Formula
To convert acres to hectares, multiply the acre value by 0.40468564224. One acre is approximately 0.4 hectares.
Complete Guide to Acres to Hectares Conversion
What is a Acres?
An acre is a unit of land area used primarily in the US and UK, equal to 43,560 square feet or about 4,047 square meters. It's commonly used for measuring farmland, estates, and large properties.
What is a Hectares?
A hectare (ha) is a metric unit of area equal to 10,000 square meters or 100 meters × 100 meters. It's the standard for land measurement in agriculture and forestry worldwide.
How the Conversion Works
Multiply acres by 0.40468564224 to get hectares. This factor is derived from the exact definitions of both units in metric terms.
Why This Conversion Matters
This conversion is essential for international real estate, agricultural trade, environmental reporting, and any land-related transactions across borders.
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
To convert acres to hectares, multiply the acre value by 0.40468564224. One acre is approximately 0.4 hectares.
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.
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Popular Acres to Hectares Conversions
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When You'll Need This Conversion
International Land Sales
Convert US farmland and property listings to hectares for international buyers and investors.
Agricultural Planning
Convert crop acreage to hectares for global agricultural reports and comparisons.
Environmental Studies
Convert forest and conservation area measurements between US and international reporting standards.
Property Development
Translate land plot sizes for international development projects and planning permits.
Pro Tips for Accurate Conversions
Use "multiply by 0.4" for estimates
For quick mental math, multiply acres by 0.4 to get approximate hectares (2.4% under, but close enough).
Know key benchmarks
1 acre ≈ 0.4 ha, 2.5 acres ≈ 1 ha, 100 acres ≈ 40 ha. Use these for quick estimates.
Football field reference
An American football field is about 1.32 acres or 0.53 hectares. A soccer pitch is about 1.8 acres or 0.7 ha.
Common Mistakes to Avoid
Confusing acres with hectares
A hectare is 2.47× larger than an acre. Quoting the wrong unit can significantly misrepresent land size.
Always verify which unit is being used, especially in international transactions.
Using the wrong conversion direction
Acres to hectares: multiply by 0.4. Hectares to acres: multiply by 2.47.
Remember: hectares are bigger, so you get a smaller number when converting acres to hectares.
History & Background
The acre originated in medieval England as the amount of land a yoke of oxen could plow in one day. The hectare was created during the French Revolution as part of the metric system.
Key Milestones
The acre was defined as a strip of land 1 furlong (660 ft) long and 1 chain (66 ft) wide.
The hectare was introduced in France as part of the metric system (10,000 m²).
The hectare became the standard for land measurement in most of the world.
Global Usage Today
The US, UK, and a few other countries use acres. Most of the world uses hectares for agricultural and land area measurements.
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.