Acres to square miles

Multiply acres by 0.0015625 to get square miles.

1 ac = 0.0015625 mi²NIST HB 44

Convert

1mi²

640 ac = 1 mi²

How to convert acres to square miles

The square mile is exactly 2 589 988.110336 m² (1609.344 m squared). The acre is exactly 43 560 square feet (4046.8564224 m²).

Worked example — 640 ac: 640 × 0.0015625 = 1 mi².

Acres to square miles table

Common conversions. The reverse table is on square miles to acres.
Acres	Square miles
1 ac	0.0015625 mi²
10 ac	0.015625 mi²
100 ac	0.15625 mi²
320 ac	0.5 mi²
640 ac	1 mi²
1,000 ac	1.5625 mi²
1,280 ac	2 mi²
2,560 ac	4 mi²
6,400 ac	10 mi²

Reverse and related

square miles → acresreverse conversion ac → ft²1 ac = 43,560 ft² ac → m²1 ac = 4,046.8564 m² ha → ac1 ha = 2.4711 ac ac → ha1 ac = 0.404686 ha km² → mi²1 km² = 0.386102 mi² mi² → km²1 mi² = 2.59 km²

About acres and square miles

Acre (ac)

1 ac = 0.0015625 mi²

Definition. Exactly 43 560 square feet (4046.8564224 m²)

History and origin

The acre began as the area a yoke of oxen could plough in a day, later fixed as 43 560 square feet, or one furlong by one chain. It equals about 4047 square metres.

Current use

Acres are the customary measure for land, farm plots and larger properties in the United States and United Kingdom.

Source: NIST Handbook 44, Appendix C (area); 1959 yard-and-pound agreement

Square mile (mi²)

1 mi² = 640 ac

Definition. Exactly 2 589 988.110336 m² (1609.344 m squared)

History and origin

The square mile is a square one mile on each side, built from the statute mile. It equals about 2.59 square kilometres, or 640 acres.

Current use

Square miles measure land, counties and regions in the United States and United Kingdom.

Source: NIST Handbook 44, Appendix C (area); 1959 yard-and-pound agreement

Where people use this

Acres: land and farm plots, US real estate. Square miles: land and county area. 640 acres is exactly 1 square mile.

How we know this is right

The factor is fixed by the standards that define the units, not chosen — so it is exact, not a measurement:

1 mi² = 640 ac, so 1 ac = 1 ÷ 640 = 0.0015625 mi².

Every value is carried to full double precision; the display is rounded.

Both units are defined in NIST Handbook 44, Appendix C (area); 1959 yard-and-pound agreement.

Questions people ask

How many square miles is an acre?

One acre is about 0.00156 square miles (one 640th).

How many square miles is 1000 acres?

1000 acres is about 1.56 square miles.

How many acres make a square mile?

It takes exactly 640 acres to make one square mile.

All acre conversions

Acres to hectares1 ac = 0.404686 ha Acres to square feet1 ac = 43,560 ft² Acres to square metres1 ac = 4,046.8564 m² Hectares to acres1 ha = 2.4711 ac Square feet to acres1 ft² = 0.0000229568 ac Square metres to acres1 m² = 0.000247105 ac Square miles to acres1 mi² = 640 ac