About the ac to km² calculation
One acre is exactly 0.00404686 square kilometers, so converting between them is a single multiplication. Enter any value above and the result updates as you type. The standard land unit in the US and UK — originally the area one ox team could plough in a day. The usual scale for reporting the area of cities and regions.
Formula
km² = ac × 0.00404686
1 ac = 0.00404686 km²
1 km² = 247.105 acWorked example
To convert 1 ac, multiply by 0.00404686: 1 × 0.00404686 = 0.00404686 km².
Frequently asked questions
How many square kilometers are in a acre?
There are 0.00404686 square kilometers in one acre. To convert any amount, multiply the number of acres by 0.00404686.
How do I convert square kilometers back to acres?
Divide instead of multiplying, or equivalently multiply by 247.105. One square kilometer is 247.105 acres.
Is this conversion exact?
Yes. Since the international agreement of 1959, the relationship between acres and square kilometers is defined exactly rather than measured, so the only rounding here is in how many decimal places we show.
Where is each of these units used?
Acres: the standard land unit in the US and UK — originally the area one ox team could plough in a day. Square Kilometers: the usual scale for reporting the area of cities and regions.
Sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units