Home › Unit Conversion › Square kilometers to Square miles
Square kilometers to Square miles (km² to mi²)
Convert square kilometers to square miles: 1 km² = 0.386102 mi². Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.
Formula
1 km² = 0.386102 mi²
square miles = square kilometers × 0.3861021585 — reverse: square kilometers = square miles × 2.58998811
The factor is derived from the SI definitions of both units (base unit: m2) as listed in NIST SP 811; results on this page are shown to 6 significant figures, the API returns up to 12.
Worked examples
- 5 km² = 1.93051 mi²
- 12.5 km² = 4.82628 mi²
- 100 km² = 38.6102 mi²
Square kilometers to square miles conversion table
| Square kilometers (km²) | Square miles (mi²) |
|---|---|
| 1 | 0.386102 |
| 2 | 0.772204 |
| 3 | 1.15831 |
| 4 | 1.54441 |
| 5 | 1.93051 |
| 6 | 2.31661 |
| 7 | 2.70272 |
| 8 | 3.08882 |
| 9 | 3.47492 |
| 10 | 3.86102 |
| 15 | 5.79153 |
| 20 | 7.72204 |
| 25 | 9.65255 |
| 30 | 11.5831 |
| 40 | 15.4441 |
| 50 | 19.3051 |
| 75 | 28.9577 |
| 100 | 38.6102 |
| 200 | 77.2204 |
| 250 | 96.5255 |
| 500 | 193.051 |
| 1000 | 386.102 |
FAQ
How many square miles are in one square kilometer?
1 km² = 0.386102 mi². The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.
What is the formula to convert square kilometers to square miles?
Multiply the value in square kilometers by 0.3861021585: square miles = square kilometers × 0.3861021585. For example, 5 km² = 1.93051 mi².
How do I convert square miles back to square kilometers?
Multiply by the inverse factor 2.58998811 (square kilometers = square miles × 2.58998811), or use the square miles-to-square kilometers page.
Related conversions
Machine access
- API:
GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=km2&to_unit=mi2 - MCP: server
https://tttkmbb.com/mcp, toolconvert_unitswith{"value":5,"from_unit":"km2","to_unit":"mi2"} - Markdown: https://tttkmbb.com/conversion/square-km-to-square-miles.md · JSON: https://tttkmbb.com/conversion/square-km-to-square-miles.json (add
?value=for a result) · Units: /api/v1/units?quantity=area - OpenAPI operationId:
convert_units. Freshness:static. Authentication: none.