Convert square miles to acres
Square mile (mi²) to acre (ac). One square mile equals 640 acres.
Formula
Square mile to acre conversion table
| Square miles | Acres | Acres | Square miles |
|---|---|---|---|
| 1 mi² | 640 ac | 1 ac | 0.001563 mi² |
| 2 mi² | 1280 ac | 2 ac | 0.003125 mi² |
| 3 mi² | 1920 ac | 3 ac | 0.004687 mi² |
| 5 mi² | 3200 ac | 5 ac | 0.007813 mi² |
| 10 mi² | 6400 ac | 10 ac | 0.015625 mi² |
| 20 mi² | 12800 ac | 20 ac | 0.03125 mi² |
| 50 mi² | 32000 ac | 50 ac | 0.078125 mi² |
| 100 mi² | 64000 ac | 100 ac | 0.15625 mi² |
| 500 mi² | 320000 ac | 500 ac | 0.78125 mi² |
| 1000 mi² | 640000 ac | 1000 ac | 1.5625 mi² |
To convert square miles to acres, multiply the number of square miles by 640. One square mile equals 640 acres, and one acre equals 0.001563 square miles, so the relationship is fixed and exact. As a worked example, 10 mi² comes to 6400 ac. Enter your own figure in the converter above to get an instant answer, or use the swap button to flip the direction. This is a area conversion, and like every tool on UnitGlide it runs locally in your browser with no account or upload required. The table further down shows a range of common square mile values already worked out in acres, plus the reverse acre to square mile direction, which is handy for quick reference or double-checking a result by hand.
Frequently asked questions
How many acres are in a square mile?
One square mile equals 640 acres. The ratio is constant, so you can multiply any number of square miles by 640 to get acres.
What is the formula to convert square miles to acres?
Use acres = square miles × 640. UnitGlide applies this exact formula for every value, so results stay accurate across the whole range.
How do I convert acres back to square miles?
Go the other way by using one acre equals 0.001563 square miles. You can also press the swap button in the converter above to flip the direction in one click.
Is this square mile to acre converter accurate?
Yes. It uses internationally defined SI conversion factors, as maintained by the BIPM, and all math runs in your browser so nothing is rounded away on a server. For everyday use the displayed precision is more than enough.