How do I convert square miles to acres?

Multiply the square mile value by 640. So x mi² × 640 = the equivalent in ac.

What is 5 square miles in acres?

5 square miles equals 3200 acres.

What is 10 square miles in acres?

10 square miles equals 6400 acres.

What is 100 square miles in acres?

100 square miles equals 64000 acres.

How do I convert back from acres to square miles?

Multiply the acre value by 0.0015625. For example, 1 ac = 0.0015625 mi².

Is the square mile bigger than the acre?

Yes. 1 square mile is larger than 1 acre — specifically 640 times larger.

Are these conversion factors exact?

Yes. Since the 1959 international yard and pound agreement, imperial/US units are defined exactly in terms of metric units, so the factor used here (640) is exact within IEEE 754 double precision.

Square miles to Acres Converter

1 mi² = 640 ac (square mile → acre)

1 mi² = 640 ac

1 square mile equals 640 acres. To convert square miles to acres, multiply the square mile value by 640. For quick reference: 1 mi² = 640 ac, 5 mi² = 3200 ac, 10 mi² = 6400 ac, 100 mi² = 64000 ac.

From

640

FormulaAcres = Square miles × 640

Quick

When to use square miles → acres

Square miles to acres multiplies by 640 exactly. A 2.5 sq mi tract is 1,600 acres. The conversion is lossless and historical — the entire US Public Land Survey System is built on it. When you see US farm or ranch acreage in round multiples of 40, 160, or 640, you're looking at survey-system geometry, and this conversion translates it back to the square-mile grid it came from.

How to convert square miles to acres

Take your value
Start with your value in square miles.
Multiply by 640
Multiply the square mile value by 640. This is the exact conversion factor from square miles to acres.
Read the result
The product is your value in acres. For example, 5 mi² × 640 = 3200 ac.

Conversion formula

The exact factor from square miles to acres is 640.

Acres = Square miles × 640

Square miles to Acres conversion table

Fifty common reference values, hand-picked for skim utility. Use the calculator above for any value not listed.

Conversion table from square miles to acres
Square miles (mi²)	Acres (ac)
0.1 mi²	64 ac
0.25 mi²	160 ac
0.5 mi²	320 ac
1 mi²	640 ac
2 mi²	1280 ac
3 mi²	1920 ac
4 mi²	2560 ac
5 mi²	3200 ac
6 mi²	3840 ac
7 mi²	4480 ac
8 mi²	5120 ac
9 mi²	5760 ac
10 mi²	6400 ac
12 mi²	7680 ac
15 mi²	9600 ac
20 mi²	12800 ac
25 mi²	16000 ac
30 mi²	19200 ac
40 mi²	25600 ac
50 mi²	32000 ac
60 mi²	38400 ac
70 mi²	44800 ac
75 mi²	48000 ac
80 mi²	51200 ac
90 mi²	57600 ac
100 mi²	64000 ac
120 mi²	76800 ac
150 mi²	96000 ac
200 mi²	128000 ac
250 mi²	160000 ac
300 mi²	192000 ac
400 mi²	256000 ac
500 mi²	320000 ac
600 mi²	384000 ac
750 mi²	480000 ac
800 mi²	512000 ac
1000 mi²	640000 ac
1200 mi²	768000 ac
1500 mi²	960000 ac
2000 mi²	1280000 ac
2500 mi²	1600000 ac
3000 mi²	1920000 ac
4000 mi²	2560000 ac
5000 mi²	3200000 ac
7500 mi²	4800000 ac
10000 mi²	6400000 ac
20000 mi²	12800000 ac
50000 mi²	32000000 ac
100000 mi²	64000000 ac
1000000 mi²	640000000 ac

Real-world reference

A US survey 'section' is exactly 1 square mile (640 acres). Los Angeles covers about 469 sq mi. In acres, that gives you: 1 mi² = 640 ac, 10 mi² = 6400 ac, 100 mi² = 64000 ac.

Frequently asked questions

How many acres are in 1 square mile?: 1 square mile equals 640 acres.
How do I convert square miles to acres?: Multiply the square mile value by 640. So x mi² × 640 = the equivalent in ac.
What is 5 square miles in acres?: 5 square miles equals 3200 acres.
What is 10 square miles in acres?: 10 square miles equals 6400 acres.
What is 100 square miles in acres?: 100 square miles equals 64000 acres.
How do I convert back from acres to square miles?: Multiply the acre value by 0.0015625. For example, 1 ac = 0.0015625 mi².
Is the square mile bigger than the acre?: Yes. 1 square mile is larger than 1 acre — specifically 640 times larger.
Are these conversion factors exact?: Yes. Since the 1959 international yard and pound agreement, imperial/US units are defined exactly in terms of metric units, so the factor used here (640) is exact within IEEE 754 double precision.

About the square mile and the acre

The square mile

The square mile is the imperial unit for large land areas, standard in US geography and census data. One square mile is exactly 2.589988110336 km² (1.609344 km squared), or 640 acres — the basis of the US Public Land Survey System's square-mile 'sections'. Los Angeles covers about 469 square miles.

The acre

The acre is the traditional imperial unit for land, still the standard for US and UK property, farmland, and parkland. One acre is exactly 4,046.8564224 m² — historically the area a yoke of oxen could plough in a day, standardised as 1 chain by 1 furlong (66 × 660 feet, or 43,560 square feet). An American football field including end zones is about 1.32 acres.

Acres to Square miles

ac → mi²

Square meters to Square feet

m² → ft²

Square meters to Acres

m² → ac

Square meters to Hectares

m² → ha

Square meters to Square kilometers

m² → km²

Square meters to Square miles

m² → mi²