Convert Acres to Square Kilometres (ac to km2)
1 acre (ac) = 0.004046856422 square kilometres (km²). 1 km² = 247.1053815 ac. Example: 15 ac = 15 × 0.004046856422 = 0.06070284634 km².
Also searched as acres to km2, acres in km2, acres into square kilometres, ac to km2, ac in square kilometres, ac into square kilometre, acre to square kilometre, ac to square kilometres converter, acres to square kilometers and how many square kilometres in an acre.
1 ac = 0.004046856422 km²
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk acre to square kilometre converter to paste a column from Excel.
How to Convert Acre to Square Kilometre
- 1 ac = 0.004046856422 km²
- 1 km² = 247.1053815 ac
- Example: convert 15 ac to km²: 15 ac = 15 × 0.004046856422 km² = 0.06070284634 km²
Formula
km² = ac × 0.0040468564224
or km² = ac ÷ 247.1053814672
Derivation from SI units:
- 1 acre = 43 560 ft² = 4 046.856 422 4 m² (international foot; the US survey foot was retired at the end of 2022)
- 1 km² = (1000 m)² = 10⁶ m² = 100 ha
- 1 ac = 4046.8564224 m² ÷ 1000000 m² per km² = 0.0040468564224 km²
Both units are defined exactly, so the factor is exact. Acre definition: acre; Square Kilometre definition: square kilometre.
Worked examples
- A reading of 2 ac converts to 0.008093712845 km².
2 ac × 0.004046856422 = 0.008093712845 km² - A value of 20 ac is 0.08093712845 km².
20 ac × 0.004046856422 = 0.08093712845 km²
Acre to Square Kilometre conversion table
| Acres (ac) | Square Kilometres (km²) |
|---|---|
| 0.1 ac | 0.0004046856422 km² |
| 0.25 ac | 0.001011714106 km² |
| 0.5 ac | 0.002023428211 km² |
| 1 ac | 0.004046856422 km² |
| 2 ac | 0.008093712845 km² |
| 2.47105 ac | 0.009999984563 km² |
| 5 ac | 0.02023428211 km² |
| 10 ac | 0.04046856422 km² |
| 20 ac | 0.08093712845 km² |
| 40 ac | 0.1618742569 km² |
| 100 ac | 0.4046856422 km² |
| 160 ac | 0.6474970276 km² |
| 640 ac | 2.58998811 km² |
Where it's used
Acres are used for US, UK and Indian land and property listings, while square kilometres appear in city, lake and country areas. Both measure area, so the conversion is a fixed factor.
Acre to other area units
| Conversion | 1 ac equals |
|---|---|
| acre to square kilometre | 0.004046856422 km² |
| acre to square meter | 4046.856422 m² |
| acre to square centimeter | 40468564.22 cm² |
| acre to square foot | 43560 ft² |
| acre to square inch | 6272640 in² |
| acre to hectare | 0.4046856422 ha |
| acre to square millimeter | 4046856422 mm² |
| acre to square yard | 4840 yd² |
Show 1 more units
| acre to square mile | 0.0015625 mi² |
|---|
Frequently asked questions
How many square kilometres are in 1 acre?
1 ac = 0.004046856422 km².
How do I convert acres to square kilometres?
Multiply the value in ac by 0.004046856422, or divide it by 247.1053815. For example, 15 ac × 0.004046856422 = 0.06070284634 km².
Is the ac to km² conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- NIST Handbook 44, Appendix C: General Tables of Units of Measurement, National Institute of Standards and Technology , Appendix C, units of area.
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Acres to Square Kilometres (ac to km2). Retrieved October 25, 2026, from https://scientificconverters.com/area/acres-to-square-kilometers/
IEEE
Scientific Converters, "Convert Acres to Square Kilometres (ac to km2)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/area/acres-to-square-kilometers/