Convert square inches to square millimeters

Explanation

From this page you can convert square inches to square millimeters (or sq in to mm²) simply, by using the application above.

In case you are wondering, to convert from square inches to square millimeters you need to multiply by 645.16. This factor is calculated using the respective definitions of the two units you can find below.

Formula

1 sq in=645.16 mm²

square inchessq in

dimension	area
symbol	sq in, in²
search alias	in2, sqin

The square inch (sq in, in²) is a derived unit of area in the international mass and length units.

Definition of the square inch

One square inch is the superficial area equivalent to that of a square each side of which measures one inch.

Value

One square inch is equal to ¹⁄₁₄₄ of a square foot.

From the Weights and Measures Act of 1985: PART VI: Measurement of area

Value in terms of the SI

One square inch is equivalent to 645.16 square millimeters.

International area units

square inch	sq in
square foot	sq ft	144 square inches
square yard	sq yd	9 square feet
square mile	sq mi	3 097 600 square yards

The International Mass and Length Units

The International Mass and Length Units are units based on the international yard and the international pound.

They were created in 1959 when Australia, Canada, New Zealand, South Africa, the United Kingdom and the United States of America agreed upon a common definition of the yard and the pound.

square millimetersmm²

dimension	area
system	International system of units (SI)
symbol	mm², sq mm

The square millimeter (mm², sq mm) is a derived area unit in the International System of Units.

Definition of the square millimeter

One square millimeter is a superficial area equivalent to that of a square whose sides are one millimeter long.

Equivalences

One square millimeter is equivalent to:

SI Area Units

square millimeter	mm²	0.000001
square centimeter	cm²	0.0001
square meter	m²	1
square kilometer	km²	1000000

The International System of Units

The International System of Units or SI (from the French Système international (d'unité)), also called metric system in the U.S., is a coherent system of units that was published 1960. It is official in nearly every country.

The General Conference on Weights and Measures (Conférence générale des poids et mesures) is tasked with overseeing the SI.