Convert acres to square miles
1 ac = 0.0015625 mi² — exactly. Both units are defined against the SI, so this factor is a fraction, not an approximation.
0.001 562 5mi²
Exact decimal: 0.0015625
As a fraction: 1/640
1 ac = 0.0015625 mi²
How to convert acres to square miles
Multiply the number of acres by 0.0015625 to get square miles.
The exact factor is 0.0015625 — as a fraction, 1/640.
Acre: Exactly 4840 square yards — historically a day of ploughing.
Acre to Square mile conversion table
| Acres (ac) | Square miles (mi²) |
|---|---|
| 1 ac | 0.001 562 5 |
| 2 ac | 0.003 125 |
| 3 ac | 0.004 687 5 |
| 5 ac | 0.007 812 5 |
| 10 ac | 0.015 625 |
| 20 ac | 0.031 25 |
| 25 ac | 0.039 062 5 |
| 50 ac | 0.078 125 |
| 100 ac | 0.156 25 |
| 250 ac | 0.390 625 |
| 500 ac | 0.781 25 |
| 1000 ac | 1.5625 |
Square mile to Acre conversion table
| Square miles (mi²) | Acres (ac) |
|---|---|
| 1 mi² | 640 |
| 2 mi² | 1280 |
| 3 mi² | 1920 |
| 5 mi² | 3200 |
| 10 mi² | 6400 |
| 20 mi² | 12 800 |
| 25 mi² | 16 000 |
| 50 mi² | 32 000 |
| 100 mi² | 64 000 |
| 250 mi² | 160 000 |
| 500 mi² | 320 000 |
| 1000 mi² | 640 000 |
Frequently asked
How many square miles are in a acre?
One acre equals 0.0015625 square miles (ac → mi²). That figure is exact, not rounded.
How do you convert acres to square miles?
Multiply the number of acres by 0.0015625 to get square miles.
What is 1 mi² in acres?
One square mile is 640 acres.
What is 10 ac in mi²?
10 ac = 0.015 625 mi².
What exactly is a acre?
Exactly 4840 square yards — historically a day of ploughing.