Square Feet to Square Miles
Convert square feet to square miles instantly — one square foot is 3.58701e-08 square miles.
| Square Feet | Square Miles |
|---|---|
| 1 ft² | 3.58701e-08 mi² |
| 2 ft² | 7.17401e-08 mi² |
| 3 ft² | 1.0761e-07 mi² |
| 5 ft² | 1.7935e-07 mi² |
| 10 ft² | 3.58701e-07 mi² |
| 25 ft² | 8.96752e-07 mi² |
| 50 ft² | 1.7935e-06 mi² |
| 100 ft² | 3.58701e-06 mi² |
How to use
- Enter a value in the Square Feet field.
- The Square Miles figure appears immediately — no button to press.
- Typing in the Square Miles field converts back to Square Feet the same way.
- Use the reference table for the values that come up most often.
Square Feet to Square Miles formula
The factor from square feet to square miles is 3.58700643e-08.
mi² = ft² × 3.58700643e-08
Why this factor: the square foot and the square mile are both defined against the square meter, so dividing one definition by the other gives 3.58700643e-08 directly. Both definitions are set out in full below.
To go the other way, divide by 3.58700643e-08 — or use the Square Miles to Square Feet converter, which is the same calculation reversed.
Worked example
Start with 250 ft². Multiply by 3.58700643e-08 to get 8.96752e-06 mi².
250 ft² × 3.58700643e-08 = 8.96752e-06 mi²
The converter above does this for any value you type, in either direction.
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.
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.
Square Feet vs Square Miles
The square foot and the square mile 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 miles are in a square foot?
One square foot equals 3.58700643e-08 square miles.
What is the formula to convert square feet to square miles?
Multiply the number of square feet by 3.58700643e-08. To reverse it, divide by 3.58700643e-08 instead.
How do I convert square miles back to square feet?
Divide by 3.58700643e-08, which is the same as multiplying by 27878400.
How many square miles are in 10 square feet?
10 ft² works out to 3.58701e-07 mi².
How is the square foot defined?
Exactly 0.09290304 square meter, following from the exact 0.3048 m foot.