Convert acres to square kilometers
Converting acres to square kilometers is a common area task, whether you are checking a recipe, a spec sheet, a travel distance or a homework problem. Since 1 ac equals 0.00404686 km², the math is a single multiplication — and this page does it for you instantly, with the formula, a table of common values and answers to the questions people ask most.
Exact factor
How to convert acres to square kilometers
To convert acres to square kilometers, multiply the number of acres by 0.00404686. For example, 10 ac × 0.00404686 = 0.0404686 km².
km² = ac × 0.00404686
- Write down the value in acres you want to convert.
- Multiply it by 0.00404686 (the exact ac→km² factor).
- The result is your value in square kilometers. Check it below with the converter or the table.
Conversion table
Common values of acres and their equivalents in square kilometers:
| ac | km² |
|---|---|
| 1 | 0.00404686 |
| 2 | 0.00809371 |
| 3 | 0.0121406 |
| 4 | 0.0161874 |
| 5 | 0.0202343 |
| 10 | 0.0404686 |
| 20 | 0.0809371 |
| 25 | 0.101171 |
| 50 | 0.202343 |
| 100 | 0.404686 |
| 250 | 1.01171 |
| 500 | 2.02343 |
About these units
Acre (ac). An acre equals exactly 4,046.8564224 square meters, or 43,560 square feet. It is the traditional land unit in the US and UK, about 0.4 hectares.
Square Kilometer (km²). A square kilometer equals one million square meters, or 100 hectares. Cities, lakes and countries are measured in square kilometers.
Frequently asked questions
How do I convert acres to square kilometers?
To convert acres to square kilometers, multiply the number of acres by 0.00404686. For example, 10 ac × 0.00404686 = 0.0404686 km². Or skip the math: type the value into the converter at the top of this page and the result updates instantly.
How many square kilometers are in 1 acre?
1 ac = 0.00404686 km². That is the fixed relationship used by this converter and by international standards.
How many acres are in 1 square kilometer?
1 km² = 247.105 ac. If you are converting in the opposite direction, use our Square Kilometer to Acre converter for the dedicated table and FAQ.
Is the acres to square kilometers conversion exact?
Yes. Both units are defined by international agreement, so the factor of 0.00404686 is exact. Displayed results are rounded to 6 significant digits only for readability.
What is acre used for?
An acre equals exactly 4,046.8564224 square meters, or 43,560 square feet. It is the traditional land unit in the US and UK, about 0.4 hectares.