CalcPairsSquare Miles to Square Kilometers Converter (sq mi to km²)
One square mile is 2.589988 km². A square mile is a mile (1.609344 km) squared — 1.609344² = 2.589988110336 — so square miles × 2.589988 gives square kilometres, and Greater London's 607 sq mi becomes 1,572 km².
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How this conversion works
Cities, counties, national parks and lakes are measured in square miles in the US and square kilometres elsewhere. Type either side: Yellowstone's 3,471 sq mi is 8,990 km²; a 100 km² nature reserve is 38.61 sq mi.
As with all area conversions, the factor is the length factor squared — which is why a unit only 1.6× longer produces an area 2.59× larger. One square mile is also exactly 640 acres, a bridge between this page and the acres converter.
The exact formula
square kilometres = square miles × 2.589988110336
2.589988110336 is 1.609344² — the mile-to-kilometre factor, squared. The reverse is square miles = square kilometres ÷ 2.589988110336.
Square miles to Square kilometers conversion table
| Square miles (sq mi) | Square kilometers (km²) |
|---|---|
| 1 | 2.589988 |
| 2 | 5.179976 |
| 3 | 7.769964 |
| 4 | 10.359952 |
| 5 | 12.949941 |
| 6 | 15.539929 |
| 7 | 18.129917 |
| 8 | 20.719905 |
| 9 | 23.309893 |
| 10 | 25.899881 |
| Square miles (sq mi) | Square kilometers (km²) |
|---|---|
| 11 | 28.489869 |
| 12 | 31.079857 |
| 13 | 33.669845 |
| 14 | 36.259834 |
| 15 | 38.849822 |
| 16 | 41.43981 |
| 17 | 44.029798 |
| 18 | 46.619786 |
| 19 | 49.209774 |
| 20 | 51.799762 |
| Square miles (sq mi) | Square kilometers (km²) |
|---|---|
| 21 | 54.38975 |
| 22 | 56.979738 |
| 23 | 59.569727 |
| 24 | 62.159715 |
| 25 | 64.749703 |
| 26 | 67.339691 |
| 27 | 69.929679 |
| 28 | 72.519667 |
| 29 | 75.109655 |
| 30 | 77.699643 |
| Square miles (sq mi) | Square kilometers (km²) |
|---|---|
| 31 | 80.289631 |
| 32 | 82.87962 |
| 33 | 85.469608 |
| 34 | 88.059596 |
| 35 | 90.649584 |
| 36 | 93.239572 |
| 37 | 95.82956 |
| 38 | 98.419548 |
| 39 | 101.009536 |
| 40 | 103.599524 |
| Square miles (sq mi) | Square kilometers (km²) |
|---|---|
| 41 | 106.189513 |
| 42 | 108.779501 |
| 43 | 111.369489 |
| 44 | 113.959477 |
| 45 | 116.549465 |
| 46 | 119.139453 |
| 47 | 121.729441 |
| 48 | 124.319429 |
| 49 | 126.909417 |
| 50 | 129.499406 |
| Square miles (sq mi) | Square kilometers (km²) |
|---|---|
| 75 | 194.249108 |
| 100 | 258.998811 |
Frequently asked questions
How many square kilometres are in a square mile?
2.589988110336 km² exactly.
How many acres are in a square mile?
Exactly 640 acres — a square mile is a survey 'section' of land in the US system.
How big is a square kilometre in miles terms?
0.386102 square miles. A square kilometre is a square about 0.62 miles on each side.