How to Convert Acres to Hectares (ac to ha)
Area conversions are everyday maths in Singapore property: HDB flats are listed in square metres while condo listings and PSF prices use square feet. This guide shows how to convert acres into hectares by hand, with examples and a quick-reference table.
The conversion
To convert acres to hectares, multiply the value by 0.4046856422. To go the other way, divide by the same number (or multiply by 2.4710538147). For a quick estimate, multiply by about 0.4.
Hectares = acres × 0.4046856422
Worked examples
- 3 ac = 1.2141 ha
- 12.5 ac = 5.0586 ha
- 75 ac = 30.3514 ha
Acres to Hectares table
| Acres | Hectares |
|---|---|
| 1 ac | 0.404686 ha |
| 2 ac | 0.809371 ha |
| 5 ac | 2.0234 ha |
| 10 ac | 4.0469 ha |
| 20 ac | 8.0937 ha |
| 25 ac | 10.1171 ha |
| 50 ac | 20.2343 ha |
| 100 ac | 40.4686 ha |
| 250 ac | 101.1714 ha |
| 500 ac | 202.3428 ha |
| 1,000 ac | 404.6856 ha |
Common questions
Is ac to ha exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Hectares to Acres converter.
Mistakes to avoid
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Background
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
For any value, use the Acres to Hectares Converter or browse all area converters.
Run your own numbers: Acres to Hectares Converter