📏 Square miles to Acres Converter
Convert square miles (mi²) to acres (ac) instantly, with the formula, a worked example and a conversion table.
Quick answer: 1 square mile (mi²) = 640 acres (ac). Formula: ac = mi² × 640.
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Square miles to Acres Converter inputs
Result
Square miles to Acres conversion table
| Square miles (mi²) | Acres (ac) |
|---|---|
| 0.1 mi² | 64 ac |
| 0.5 mi² | 320 ac |
| 1 mi² | 640 ac |
| 2 mi² | 1,280 ac |
| 3 mi² | 1,920 ac |
| 5 mi² | 3,200 ac |
| 10 mi² | 6,400 ac |
| 20 mi² | 12,800 ac |
| 25 mi² | 16,000 ac |
| 50 mi² | 32,000 ac |
| 100 mi² | 64,000 ac |
| 1,000 mi² | 640,000 ac |
Other area conversions
How to convert square miles to acres
Multiply the number of square miles by 640 to get acres: ac = mi² × 640.
Example: 5 mi² = 3,200 ac.
The square mile (mi²) and the acre (ac) are both units of area. Need the opposite direction? Use the ac to mi² converter.
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Metric and imperial units
The metric system (SI) is used by almost every country and by science worldwide. Its units scale by powers of ten – 1 kilometer is 1,000 meters, 1 meter is 100 centimeters – which makes conversions inside the system easy. The imperial and US customary systems (inches, feet, pounds, gallons) are still used daily in the United States and partly in the UK.
Since 1959 the inch has been defined as exactly 2.54 centimeters and the pound as exactly 0.45359237 kilograms, so conversions between the two systems are exact. Note that a US gallon (3.785 L) and an imperial gallon (4.546 L) are different – choose the right one above.
This converter covers 10 categories and 66 units: length, weight, temperature, volume, area, speed, time, data, energy, pressure.
Frequently asked questions
How many acres are in a square mile?
1 square mile = 640 acres.
How do I convert square miles to acres?
Use the formula ac = mi² × 640. For example, 5 mi² = 3,200 ac.
How do I convert acres back to square miles?
1 acre = 0.0015625 square miles. Use the ac to mi² converter linked on this page.
Are these conversions exact?
Yes – all factors use the internationally defined values (for example 1 inch = 2.54 cm exactly, 1 pound = 0.45359237 kg exactly). Results are rounded to 8 significant digits for display.