Square Miles to Square Feet
Convert square miles (mi²) to square feet (ft²). Both measure surface measurement, and the conversion comes up in real estate, farming, construction work.
The Formula
``
square feet = square miles × 27878400
square miles = square feet × 3.58700642792e-8
`
One square mile is 27,878,400 square feet, and one square feet is 3.5870e-8 square miles.
Conversion Table
| Square Miles | Square Feet |
|---|---|
| 1 mi² | 27,878,400 ft² |
| 2 mi² | 55,756,800 ft² |
| 5 mi² | 139,392,000 ft² |
| 10 mi² | 278,784,000 ft² |
| 25 mi² | 696,960,000 ft² |
| 50 mi² | 1,393,920,000 ft² |
| 100 mi² | 2,787,840,000 ft² |
| 500 mi² | 13,939,200,000 ft² |
| 1,000 mi² | 27,878,400,000 ft² |
The Other Direction
| Square Feet | Square Miles |
|---|---|
| 1 ft² | 3.5870e-8 mi² |
| 2 ft² | 7.1740e-8 mi² |
| 5 ft² | 1.7935e-7 mi² |
| 10 ft² | 3.5870e-7 mi² |
| 25 ft² | 8.9675e-7 mi² |
| 50 ft² | 1.7935e-6 mi² |
| 100 ft² | 3.5870e-6 mi² |
| 500 ft² | 1.7935e-5 mi² |
| 1,000 ft² | 3.5870e-5 mi² |
What Each Unit Is
Square Miles (mi²) — 640 acres, or 2.589988 square kilometres. The unit of the US Public Land Survey System, which divided the west into square-mile sections.
Square Feet (ft²) — the area of a square one foot on each side, or 0.092903 square metres. The imperial unit US and UK property is advertised in.
A Sense of Scale
A survey township is 36 square miles- San Francisco is 47 square miles
- A bedroom is 120–200 ft²
- A US home averages 2,300 ft²
- A parking space is 130 ft²
Precision
The factor 27878400 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
In Code
`javascript
const squareMileToSquareFoot = (value) => value * 27878400;
``
Where This Conversion Comes Up
- Real estate
- Farming
- Construction
- Landscaping
- Flooring
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 mi² with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 mi² becomes | Error |
|---|---|---|---|
| 0 | 27878400 | 3,819,340,800 | — |
| 1 | 27878400 | 3,819,340,800 | — |
| 2 | 27878400 | 3,819,340,800 | — |
| 3 | 27878400 | 3,819,340,800 | — |
| 4 | 27878400 | 3,819,340,800 | — |
The right number of significant figures is set by your input, not by the converter. If you measured square miles to three significant figures, the answer in square feet is only good to three — writing more digits claims precision the measurement never had.