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Square Millimeters to Square Inches Converter

Convert square millimeters (mm²) to square inches (sq in), with the formula, a conversion table and exact factors.

Change the values and press Calculate to work out your own figures.

Enter an area, choose its unit and the unit you want. The answer is exact until it is shown, and the same value appears in every other unit.

A number, fraction (3/8), mixed number (1 1/2), scientific notation (2.5e6) or a simple sum such as 2*3.
The unit you want the answer in. Swap exchanges the two units.
Result
0.00155000310001 sq in
square miles
3.86102158542 × 10⁻¹³ sq mi
acres
2.47105381467 × 10⁻¹⁰ ac
square yards
1.1959900463 × 10⁻⁶ sq yd
square feet
1.07639104167 × 10⁻⁵ sq ft
square kilometers
1 × 10⁻¹² km²
hectares
1 × 10⁻¹⁰ ha
ares
1 × 10⁻⁸ a
square meters
1 × 10⁻⁶ m²
square centimeters
0.01 cm²
square micrometers
1,000,000 µm²

1 mm² = 0.00155000310001 sq in

Show the working
  1. 1 mm² = 0.00155000310001 sq in
  2. 1 × 0.00155000310001 = 0.00155000310001 sq in

How to convert square millimeters to square inches

1 mm² = 0.00155000310001 sq in, so multiply by 0.00155000310001 to go from square millimeters to square inches. Going the other way, 1 sq in = 645.16 mm².

sq in = mm² × 0.00155000310001
mm² = sq in × 645.16

Worked example:

1 mm² = 0.00155000310001 sq in
5 × 0.00155000310001 = 0.00775001550003 sq in

Square Millimeters to square inches table

Square MillimetersSquare Inches
1 mm²0.00155000310001 sq in
2 mm²0.00310000620001 sq in
3 mm²0.00465000930002 sq in
4 mm²0.00620001240002 sq in
5 mm²0.00775001550003 sq in
6 mm²0.00930001860004 sq in
7 mm²0.0108500217 sq in
8 mm²0.0124000248 sq in
9 mm²0.0139500279001 sq in
10 mm²0.0155000310001 sq in
15 mm²0.0232500465001 sq in
20 mm²0.0310000620001 sq in
25 mm²0.0387500775002 sq in
30 mm²0.0465000930002 sq in
40 mm²0.0620001240002 sq in
50 mm²0.0775001550003 sq in
75 mm²0.1162502325 sq in
100 mm²0.155000310001 sq in
250 mm²0.387500775002 sq in
500 mm²0.775001550003 sq in
1000 mm²1.55000310001 sq in

About the units

Square Millimeters (mm²)
Square millimeters, a metric unit. Definition: BIPM SI Brochure (SI prefixes).
Square Inches (sq in)
Square inches, a US customary unit. Definition: NIST Handbook 44 Appendix C (derived from the international inch).

Formula version 0.1.0Reviewed