Square miles to Acres Converter
Convert square miles to acres. The formula used here is 1 square mile = 640 acres. The formula is ac = mi² × 640; 1 mi² is 640 ac.
A US customary and imperial area unit for regions and large land parcels.
A land area unit equal to 43,560 square feet.
Start with your value in square miles, then apply the formula below. It stays visible so you can catch rounding mistakes instead of just copying the output.
For property and construction decisions, carry the converted area with the source unit, rounding rule, and any assumptions about measured boundaries.
Area conversions square the underlying length scale, so small changes in length can become larger changes in area for large rooms or parcels. This page displays converted values with up to 4 decimal places by default.
| Square miles | Acres |
|---|---|
| 1 mi² | 640 ac |
| 10 mi² | 6,400 ac |
| 100 mi² | 64,000 ac |
Useful for real-estate, land, and property records. Use the same formula with your exact input if the measurement needs to be documented.
Useful for flooring, paint, and construction estimates. Use the same formula with your exact input if the measurement needs to be documented.
Useful for mapping, agriculture, and site planning. Use the same formula with your exact input if the measurement needs to be documented.
How do I convert square miles to acres?
Enter the value in square miles and apply ac = mi² × 640. Round the acres result after the conversion, not before.
What is 1 square mile in acres?
1 mi² equals 640 ac with the current rounding setting. Keep more decimal places when the result feeds another calculation.
What is 10 mi² in ac?
10 mi² is 6,400 ac. It appears in the lookup table so you can compare it with nearby amounts.
Can I convert acres back to square miles?
Yes. Use the reverse Acres to Square miles converter if you need to go the other direction.
How accurate is this square miles to acres conversion?
The calculator runs the formula in your browser and rounds results to 4 decimal places by default. Area conversions square the underlying length scale, so small changes in length can become larger changes in area for large rooms or parcels.