Convert acres to square kilometres
1 acre = 0.00404686 km²
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How many square kilometres are in a acre?
One acre is 0.00404685642 square kilometres. To convert any amount, multiply by 0.00404685642. Going the other way, one square kilometre is 247.105381 acres.
What is the formula to convert acre to km²?
Multiply the acre figure by 0.00404685642. So km² = acre × 0.00404685642. For a quick mental estimate, dividing by about 247.11 gets you close enough for most everyday purposes.
What does a acre actually look like?
One acre is roughly a football pitch without the ends. The acre was originally the area one man with one ox could plough in a day. It is exactly 4,840 square yards, and is still the standard unit for land in the US, UK and Canada.
And what is a square kilometre?
One square kilometre is a medium city park. The square kilometre is the standard unit for reporting the area of cities, parks and countries in the metric world.
Is this conversion exact?
Yes. Since the 1959 international yard and pound agreement, the imperial and metric systems are related by exact definitions rather than measurements — the inch is exactly 25.4 mm and the pound exactly 0.45359237 kg. Everything derived from those, including this conversion, is therefore exact. Round at the end rather than partway through, since rounding acre before converting introduces an error the conversion then multiplies.
About acre to km²
How to convert acres to square kilometres
Multiply by 0.00404685642. One acre is 0.00404685642 square kilometres, and one square kilometre is 247.105381 acres.
km² = acre × 0.00404685642
Worked example
5 acre = 0.02023428 km². For a sense of scale, one acre is roughly a football pitch without the ends, and one square kilometre is a medium city park.
About the acre
The acre was originally the area one man with one ox could plough in a day. It is exactly 4,840 square yards, and is still the standard unit for land in the US, UK and Canada.
About the square kilometre
The square kilometre is the standard unit for reporting the area of cities, parks and countries in the metric world.
Quick reference
| acres | square kilometres |
|---|---|
| 1 acre | 0.00404686 km² |
| 2 acre | 0.00809371 km² |
| 5 acre | 0.0202343 km² |
| 10 acre | 0.0404686 km² |
| 25 acre | 0.101171 km² |
| 50 acre | 0.202343 km² |
| 100 acre | 0.404686 km² |
| 1000 acre | 4.04686 km² |
Getting it right
This conversion is exact by definition, so the only limit on accuracy is how many digits you keep. Round at the end rather than partway through — rounding acre to a whole number before converting introduces an error that the conversion then multiplies.
Other area conversions
Convert square kilometres back to acres, or pick any other pair with the full unit converter. Related: acre to m², acre to ft², acre to ha.