Mi² to km²
One mi² equals 2.58998811 km². Type any number and the answer appears as you type — the maths happens in your browser.
The same value in every unit
| Unit | Value |
|---|
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Common values
| mi² | km² |
|---|---|
| 1 mi² | 2.5899881 km² |
| 2 mi² | 5.1799762 km² |
| 3 mi² | 7.7699643 km² |
| 5 mi² | 12.949941 km² |
| 10 mi² | 25.899881 km² |
| 15 mi² | 38.849822 km² |
| 20 mi² | 51.799762 km² |
| 25 mi² | 64.749703 km² |
| 50 mi² | 129.49941 km² |
| 100 mi² | 258.99881 km² |
| 500 mi² | 1294.9941 km² |
| 1000 mi² | 2589.9881 km² |
How to use
- Enter the number of mi² in the field.
- The result in km² updates on every keystroke.
- Use the table below for the values people look up most often.
Formula and reverse conversion
The formula
To convert by hand: km² = mi² × 2.58998811. Going back the other way, one km² is 0.3861021585 mi².
Where the odd number comes from
The factor is not a round number because the imperial units are defined through the metric ones by international agreement: an inch is exactly 25.4 mm and a pound is exactly 0.45359237 kg. Everything else follows from those definitions.
km² = mi² × 2.58998811
Frequently asked questions
How many km² are in one mi²?
One mi² is 2.58998811 km².
How do I convert mi² to km²?
Multiply by the factor: km² = mi² × 2.58998811.
Is the result exact?
The factors are the exact legal definitions, and up to ten significant digits are kept in the answer. Rounding happens only in the display.
How do I convert km² back to mi²?
One km² is 0.3861021585 mi² — or open the reverse page linked below.