Acres to Square Kilometers converter (ac to km²)
Convert Acres (ac) to Square Kilometers (km²) with this free calculator. Type a value, press Convert, and the page applies the same factor shown in the formula below — no rounded shortcut, and nothing is stored on a server.
Square Kilometers to Acres (km² to ac) ►
How to convert Acres to Square Kilometers
1 acre (ac) is equal to 0.00404686 square kilometers (km²).
km² = ac × 0.00404685642
Multiply the area in acres by 0.00404685642:
Example: Convert 100 ac to km²:
km² = 100 × 0.00404685642 = 0.40469 km²
What is a Acres?
The Acres (ac) is the starting or target unit on this page. Use the calculator above to convert values without looking up the factor by hand.
What is a Square Kilometers?
The Square Kilometers (km²) is the starting or target unit on this page. Use the calculator above to convert values without looking up the factor by hand.
This page converts area from Acres into Square Kilometers. One ac equals 0.004046856 km².
Acres to Square Kilometers conversion table
Common ac values and the matching km² result, calculated with the same factor as the widget. Highlight a nearby row if you want a quick check without entering a number.
| Acres (ac) | Square Kilometers (km²) |
|---|---|
| 1 ac | 0.004046856 km² |
| 10 ac | 0.040468564 km² |
| 100 ac | 0.404685642 km² |
| 500 ac | 2.02342821 km² |
| 1000 ac | 4.04685642 km² |
| 5000 ac | 20.2342821 km² |
| 10000 ac | 40.4685642 km² |
How this calculator works
The form on this page is a Acres-to-Square Kilometers converter. After you enter a number, JavaScript multiplies or rearranges it with the published conversion factor and writes the km² result in the output box. The step-by-step panel repeats the arithmetic so you can copy it into homework or a spreadsheet.
Reviewed by Hamsen, founder of GigaTables and a biology engineer. See the about page for how formulas are checked before a tool is published.
FAQ
How many km² are in 1 ac?
1 ac = 0.004046856 km².
How do I convert Acres to Square Kilometers?
Multiply the area in acres by 0.00404685642:
Is this ac to km² converter free?
Yes. GigaTables calculators are free to use in a browser. You do not need an account, and the values you type are not uploaded.