How to Convert Square millimetres to Square metres (mm² to m²)
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 millimetres into square metres by hand, with examples and a quick-reference table.
The conversion
To convert square millimetres to square metres, multiply the value by 1.000000e-06. To go the other way, divide by the same number (or multiply by 1,000,000). Because the factor is tiny, scientific notation keeps the numbers manageable.
Square metres = square millimetres × 1.000000e-06
Worked examples
- 3 mm² = 3.000000e-6 m²
- 12.5 mm² = 1.250000e-5 m²
- 75 mm² = 7.500000e-5 m²
Square millimetres to Square metres table
| Square millimetres | Square metres |
|---|---|
| 1 mm² | 1.000000e-6 m² |
| 2 mm² | 2.000000e-6 m² |
| 5 mm² | 5.000000e-6 m² |
| 10 mm² | 1.000000e-5 m² |
| 20 mm² | 2.000000e-5 m² |
| 25 mm² | 2.500000e-5 m² |
| 50 mm² | 5.000000e-5 m² |
| 100 mm² | 1.000000e-4 m² |
| 250 mm² | 0.00025 m² |
| 500 mm² | 0.0005 m² |
| 1,000 mm² | 0.001 m² |
Common questions
Is mm² to m² 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 metres to Square millimetres converter.
Mistakes to avoid
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
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
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
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.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For any value, use the Square millimetres to Square metres Converter or browse all area converters.
Run your own numbers: Square millimetres to Square metres Converter