How to Convert Square kilometres to Acres (km² to ac)
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 square kilometres into acres by hand, with examples and a quick-reference table.
The conversion
To convert square kilometres to acres, multiply the value by 247.1053814672. To go the other way, divide by the same number (or multiply by 0.0040468564). For a quick estimate, multiply by about 250.
Acres = square kilometres × 247.1053814672
Worked examples
- 3 km² = 741.3161 ac
- 12.5 km² = 3,088.82 ac
- 75 km² = 18,532.9 ac
Square kilometres to Acres table
| Square kilometres | Acres |
|---|---|
| 1 km² | 247.1054 ac |
| 2 km² | 494.2108 ac |
| 5 km² | 1,235.53 ac |
| 10 km² | 2,471.05 ac |
| 20 km² | 4,942.11 ac |
| 25 km² | 6,177.63 ac |
| 50 km² | 12,355.27 ac |
| 100 km² | 24,710.54 ac |
| 250 km² | 61,776.35 ac |
| 500 km² | 123,552.69 ac |
| 1,000 km² | 247,105.38 ac |
Common questions
Is km² to ac 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 Acres to Square kilometres converter.
Mistakes to avoid
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
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
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
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.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For any value, use the Square kilometres to Acres Converter or browse all area converters.
Run your own numbers: Square kilometres to Acres Converter