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Acres to Square Miles Converter

Convert acres to square miles and square miles to acres instantly. Bidirectional area converter with formula and common values.

ac

Square Miles

0.5

sq mi

320 ac = 0.5 sq mi

sq mi = ac ÷ 640

How to Convert Acres to Square Miles

To convert acres to square miles, divide by 640. There are exactly 640 acres in one square mile, a relationship rooted in the US survey system.

Conversion Formula

  • Acres to Square Miles: sq mi = ac ÷ 640
  • Square Miles to Acres: ac = sq mi × 640

Common Conversions

AcresSquare Miles
400.0625
1600.2500
3200.5000
6401.0000
1,2802.0000
5,0007.8125
10,00015.6250

Related

FAQ

How many acres are in a square mile?

One square mile equals exactly 640 acres.

How do I convert acres to square miles?

Divide the number of acres by 640. For example, 320 acres ÷ 640 = 0.5 square miles.

Why are there 640 acres in a square mile?

A mile is 80 chains long, and a square mile is 80 × 80 = 6,400 square chains. Since one acre is 10 square chains, one square mile contains 640 acres.

How many acres is a section of land?

A section of land is one square mile, which equals 640 acres. Townships in the US Public Land Survey System are divided into 36 sections.