One acre is exactly 0.0040468564224 square kilometers. Multiply acres by that factor, or divide by about 247.1, to get square kilometers. 1,000 acres is about 4.05 km². This direction is for putting a large US or British acreage into terms international readers understand, for example in a press release, a scientific paper or a map legend. For a farm-sized acreage, the answer is a small decimal.
Formula
Acres to Square Kilometers conversion table
| Acres | Square Kilometers |
|---|---|
| 10 ac | 0.0404686 km² |
| 20 ac | 0.0809371 km² |
| 50 ac | 0.202343 km² |
| 100 ac | 0.404686 km² |
| 200 ac | 0.809371 km² |
| 250 ac | 1.0117 km² |
| 500 ac | 2.0234 km² |
| 750 ac | 3.0351 km² |
| 1,000 ac | 4.0469 km² |
| 2,000 ac | 8.0937 km² |
| 2,500 ac | 10.1171 km² |
| 5,000 ac | 20.2343 km² |
| 10,000 ac | 40.4686 km² |
| 20,000 ac | 80.9371 km² |
| 50,000 ac | 202.3428 km² |
| 100,000 ac | 404.6856 km² |
Where you’ll use it
Ranches, wildfire perimeters, national forests and conservation purchases in the US are described in acres. When those figures go into international reporting or a metric GIS dataset, they need square kilometers. 100,000 acres is about 404.69 km². For a single farm, hectares are usually a better metric unit; square kilometers suit regional comparisons, such as setting a ranch next to the size of a city or county abroad.
Tip: For small acreages the result is a tiny number, and rounding can wipe it out. A 40-acre field is about 0.16 km², so keep at least three significant figures, or report the answer in hectares instead.