Skip to contentOMNICALC

Square mile to Acre Converter

Type a value — the answer appears instantly. 1 mi² = 640 ac.

Reviewed by the OmniCalc teamMethod verified 2026-07-01

From unit

To unit
Result

640 acres

= 2,589,990 m²= 27,878,400 ft²

equals 640 acres

Formula: ac = mi² × 640

Square mile to Acre formula

ac = mi² × 640

Convert 5 square miles to acres

  1. Start with 5 square miles.
  2. Multiply by the conversion factor: 5 × 640 = 3,200.
  3. So 5 mi² = 3,200 ac.

Square mile to Acre conversion table

Square mile to Acre conversion table
Square miles (mi²)Acres (ac)
0.01 mi²6.4 ac
0.1 mi²64 ac
0.25 mi²160 ac
0.5 mi²320 ac
1 mi²640 ac
2 mi²1,280 ac
3 mi²1,920 ac
4 mi²2,560 ac
5 mi²3,200 ac
6 mi²3,840 ac
7 mi²4,480 ac
8 mi²5,120 ac
9 mi²5,760 ac
10 mi²6,400 ac
15 mi²9,600 ac
20 mi²12,800 ac
25 mi²16,000 ac
30 mi²19,200 ac
40 mi²25,600 ac
50 mi²32,000 ac
75 mi²48,000 ac
100 mi²64,000 ac
250 mi²160,000 ac
500 mi²320,000 ac
1,000 mi²640,000 ac
5,000 mi²3,200,000 ac
10,000 mi²6,400,000 ac

Unit definitions

What is a square mile?

The square mile is the area of a one-mile square, containing 640 acres or about 2.59 square kilometres. It is used for large land areas, counties, and statistical regions in the United States. One square mile is roughly 259 hectares.

What is a acre?

The acre is exactly 4840 square yards, about 4046.86 square metres or 0.405 hectares. It is the traditional unit for land area in the United States and United Kingdom. An acre was historically the area a yoke of oxen could plough in a day.

Frequently asked questions

How many acres are in one square mile?

One square mile equals 640 acres (1 mi² = 640 ac).

How do I convert square miles to acres?

Multiply the value in square miles by 640. For example, 10 mi² × 640 = 6,400 ac.

Which is bigger — a square mile or a acre?

A square mile is bigger: one square mile contains 640 acres.

Is this square mile to acre converter free?

Yes — the converter is free, works offline once loaded, and computes instantly in your browser without sending your numbers to a server.

Conversion factors follow international definitions (SI / NIST). Last verified 2026-07-01.