How to Convert Square kilometres to Square miles (km² to sq mi)
Area conversions are everyday maths in Singapore property: HDB flats are listed in square metres while condo listings and PSF prices use square feet. This guide shows how to convert square kilometres into square miles by hand, with examples and a quick-reference table.
The conversion
To convert square kilometres to square miles, multiply the value by 0.3861021585. To go the other way, divide by the same number (or multiply by 2.5899881103). For a quick estimate, multiply by about 0.39.
Square miles = square kilometres × 0.3861021585
Worked examples
- 3 km² = 1.1583 sq mi
- 12.5 km² = 4.8263 sq mi
- 75 km² = 28.9577 sq mi
Square kilometres to Square miles table
| Square kilometres | Square miles |
|---|---|
| 1 km² | 0.386102 sq mi |
| 2 km² | 0.772204 sq mi |
| 5 km² | 1.9305 sq mi |
| 10 km² | 3.861 sq mi |
| 20 km² | 7.722 sq mi |
| 25 km² | 9.6526 sq mi |
| 50 km² | 19.3051 sq mi |
| 100 km² | 38.6102 sq mi |
| 250 km² | 96.5255 sq mi |
| 500 km² | 193.0511 sq mi |
| 1,000 km² | 386.1022 sq mi |
Common questions
Is km² to sq mi exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Square miles to Square kilometres converter.
Mistakes to avoid
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Background
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
For any value, use the Square kilometres to Square miles Converter or browse all area converters.
Run your own numbers: Square kilometres to Square miles Converter