Square metric area unit.
Square Millimeters to Square inches Converter — mm2 to in2
Convert Square Millimeter (mm2) to Square inch (in2) using the exact conversion factor (1 square millimeter = 0.0015500031 square inch). See the formula, worked examples, and conversion table.
Square Millimeters to Square inches converter
Converter
Area Converter
Convert land, construction, mapping, survey, and scientific area units.
Context values
Some unit families need one extra value for a physically accurate result.
A square inch is the area of a one-inch square.
Result = input x 1e-6 / 0.00064516.
Area uses the square meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Square Millimeters to Square inches
Comparing Square Millimeter and Square inch is common in agriculture and real estate, where US land is typically measured in acres and most of the rest of the world uses hectares. Specifically: Square metric area unit, and a square inch is the area of a one-inch square.
Formula
square inches = square millimeters × 0.00155000310001
This factor comes from each unit's defined relationship to the category's base unit: 1 square millimeter equals 0.000001 base units, and 1 square inch equals 0.00064516 base units, so dividing one by the other gives the direct square millimeter-to-square inch factor of 0.00155000310001.
Simple example
1 mm2 × 0.0015500031 = 0.0015500031 in2
1 square millimeter = 0.0015500031 square inches.
Real-world example
10 mm2 × 0.0015500031 = 0.015500031 in2
10 square millimeters = 0.015500031 square inches.
Conversion table
| Square Millimeter (mm2) | Square inch (in2) |
|---|---|
| 1 mm2 | 0.0015500031 in2 |
| 5 mm2 | 0.0077500155 in2 |
| 10 mm2 | 0.015500031 in2 |
| 25 mm2 | 0.0387500775 in2 |
| 50 mm2 | 0.077500155 in2 |
| 100 mm2 | 0.15500031 in2 |
Reverse conversion: Square inch to Square Millimeter
0.0015500031 in2 × 645.16 = 1 mm2
0.0015500031 square inches = 1 square millimeters.
square millimeters = square inches × 645.16
For a page dedicated to this direction, see Square inch to Square Millimeter.
Understanding the Square Millimeter (mm2)
Square metric area unit.
Understanding the Square inch (in2)
A square inch is the area of a one-inch square.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many square inches are in 1 square millimeter?
1 square millimeter equals 0.0015500031 square inches, using the exact defined conversion factor rather than an estimate.
How do I convert square millimeter to square inch?
Multiply the square millimeter value by 0.0015500031. The converter above does this instantly to whatever precision you set.
How do I convert square inch back to square millimeter?
Use the reverse factor: 1 square inch equals 645.16 square millimeters. You can also use the swap control in the converter above to flip the direction instantly.
What is a square millimeter?
Square Millimeter (mm2) is a unit of area.
What is a square inch?
Square inch (in2) is a unit of area.
Is the square millimeter to square inch conversion exact?
Yes. Both square millimeter and square inch are defined by fixed standards rather than physical artifacts, so the factor of 0.0015500031 used above is exact to as many digits as you choose to display.