What Is Square Mile (mi²)?
A square mile is a way to measure area. It shows how much space a piece of land covers. One square mile is the area of a square that is one mile long on each side.
People use square miles to talk about the size of large places, like cities, lakes, forests and even whole countries.
Definition
A square mile is a unit of area. It belongs to the group of imperial and US customary units.
Clear meaning: If you draw a square and each side of the square is exactly one mile long, the space inside that square is one square mile.
Main facts:
- 1 square mile = area of a square that is 1 mile by 1 mile
- 1 square mile is about 2.59 square kilometers
- 1 square mile equals 640 acres
History / Origin
The square mile comes from old English and British ways of measuring land. Long ago, land owners and rulers needed a unit that was big enough to describe farms, villages and counties.
They already used the mile to measure distance on roads. So they built a land unit from it. A square with sides of one mile gave a large and useful size, and it became the square mile.
Over time, this unit spread through the British Empire. Later, countries like the United States and others that used imperial style units kept the square mile for maps, land records and government work.
Symbol & Abbreviation
The square mile has a few common short forms.
- mi² is the symbol often used in writing and math
- sq mi is a common short form in text and maps
- You may also see square mile written out in full
All of these mean the same thing. They all show an area measured in square miles.
Current Use Around the World
Today, the square mile is still widely used in some countries, especially where imperial or US customary units are common.
Common places where square miles are used:
- United States to show the size of states, cities, counties and lakes
- United Kingdom to describe areas of regions and natural parks
- Canada sometimes, especially in older documents, although square kilometers are now more common
- Other English speaking countries in maps, books and news when talking to an international audience
Outside these places, most countries use the square kilometer as the main unit for large areas, but they may still show square miles as a second unit to help readers who know imperial units.
Example Conversions
Here are some simple conversion facts and examples to help you move between square miles and other units of area.
Between square miles and square kilometers
- 1 square mile ≈ 2.59 square kilometers
- 10 square miles ≈ 25.9 square kilometers
- 100 square miles ≈ 259 square kilometers
To change square miles to square kilometers, multiply by 2.59.
To change square kilometers to square miles, divide by 2.59.
Between square miles and acres
- 1 square mile = 640 acres
- 0.5 square mile = 320 acres
- 2 square miles = 1,280 acres
To change square miles to acres, multiply by 640.
Between square miles and square feet
- 1 mile = 5,280 feet
- 1 square mile = 5,280 × 5,280 square feet
- 1 square mile = 27,878,400 square feet
Quick real world example
If a small town covers 4 square miles, then:
- In square kilometers it is about 4 × 2.59 = 10.36 square kilometers
- In acres it is 4 × 640 = 2,560 acres
Related Units
These units are often used with or instead of the square mile when measuring area.
- Square kilometer (km²) main large area unit in the metric system
- Acre smaller land unit in imperial and US customary systems, 640 acres in one square mile
- Square yard (yd²) smaller area unit, used for fields and floors
- Square foot (ft²) very common for rooms, houses and small spaces
- Hectare (ha) metric land unit, used for farms and forests, 1 hectare is 0.003861 square miles
FAQs
What is a square mile in simple words
It is the area inside a square where each side of the square is one mile long.
Is a square mile the same as a mile
No. A mile measures distance along a line. A square mile measures area, which is space on a surface. They are related but not the same thing.
Why do people still use square miles
Many maps, laws and records in the United States and some other countries were created using this unit, so people keep using it for consistency and easy comparison.
Which is bigger, a square mile or a square kilometer
A square mile is bigger. One square mile is about 2.59 square kilometers.
How many acres are in a square mile
There are 640 acres in one square mile.
When should I use square miles instead of square kilometers
Use square miles when working with US or UK sources that already use imperial units, or when your reader is more used to miles than to kilometers.