Square Miles to Square Feet
An instant square miles-to-square feet converter, with the formula and a reference table below.
| Square Miles | Square Feet |
|---|---|
| 1 mi² | 27878400 ft² |
| 2 mi² | 55756800 ft² |
| 3 mi² | 83635200 ft² |
| 5 mi² | 139392000 ft² |
| 10 mi² | 278784000 ft² |
| 25 mi² | 696960000 ft² |
| 50 mi² | 1393920000 ft² |
| 100 mi² | 2787840000 ft² |
How to use
- Enter a value in the Square Miles field.
- The Square Feet figure appears immediately — no button to press.
- Typing in the Square Feet field converts back to Square Miles the same way.
- Use the reference table for the values that come up most often.
Square Miles to Square Feet formula
The factor from square miles to square feet is 27878400.
ft² = mi² × 27878400
Why this factor: the square mile and the square foot are both defined against the square meter, so dividing one definition by the other gives 27878400 directly. Both definitions are set out in full below.
To go the other way, divide by 27878400 — or use the Square Feet to Square Miles converter, which is the same calculation reversed.
Worked example
Take 50 mi² and multiply by the factor 27878400: the result is 1393920000 ft².
50 mi² × 27878400 = 1393920000 ft²
The converter above does this for any value you type, in either direction.
What is a square mile?
A square mile is the area of a one-mile square, used for large land areas in the US and UK.
Definition: Exactly 2,589,988.110336 square meters, and exactly 640 acres.
Where it is used: County, state and metropolitan areas, and population density in the US.
What is a square foot?
A square foot is the primary unit of floor area in the United States.
Definition: Exactly 0.09290304 square meter, following from the exact 0.3048 m foot.
Where it is used: US and Indian property listings, commercial leases, and paint and flooring coverage.
Square Miles vs Square Feet
The square mile and the square foot belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many square feet are in a square mile?
One square mile equals 27878400 square feet.
What is the formula to convert square miles to square feet?
Multiply the number of square miles by 27878400. To reverse it, divide by 27878400 instead.
How do I convert square feet back to square miles?
Divide by 27878400, which is the same as multiplying by 3.58700643e-08.
How many square feet are in 10 square miles?
10 mi² works out to 278784000 ft².
How is the square mile defined?
Exactly 2,589,988.110336 square meters, and exactly 640 acres.