Square Meters to Square Millimeters (m² to mm²)

1 square meter equals 1,000,000 square millimeters exactly.

1 square meter = 1,000,000 square millimeters

How to convert square meters to square millimeters

To convert square meters to square millimeters, multiply the number of square meters by 1,000,000. This factor is exact. To go the other way, multiply square millimeters by 0.000001.

square millimeters = square meters × 1,000,000

Example: 10 square meters = 10,000,000 square millimeters.

About these units

Square Meter (m²)

Metric (SI)Current unit

The SI unit of area: a square one meter on each side. Used for floor areas and property sizes in most of the world.

Squaring the meter was built into the metric system from the start. The French law of 18 Germinal, Year III (7 April 1795) defined the are, the land unit that gave the hectare its name, as exactly 100 square meters, so the square meter was already the foundation of metric land measure. Nobody is credited with inventing it as a separate unit. It is simply the area of a square one meter on each side, and any SI prefix that works for the meter works for it, with the prefix squared along with the unit.

That squaring catches people out: a square kilometer is one million square meters, not one thousand. Since 1983 the meter has been defined through the speed of light, so the square meter is tied to a constant of nature as well as to the second. A hectare, about the area of Trafalgar Square in London, is 10,000 square meters. In everyday terms one square meter is about 10.76 square feet. Unicode has a compatibility character for it, but the recommended way to write it is the plain superscript two: m².

The square meter is the reference unit for area on this site.

Sources: Wikipedia: Square metre; Wikipedia: Are (unit); NIST: the meter and the SI redefinition

Square Millimeter (mm²)

Metric (SI)Current unit

A square one millimeter on a side. Used for the cross-section of wires and small parts.

Gauss gets the credit for putting the millimeter at the base of a scientific measuring system. His 1832 proposal for absolute units used the millimeter, milligram and second, although the centimeter-based CGS system later won out among scientists. The square millimeter is a one-thousandth-by-one-thousandth square of a meter, so it takes a million of them to make a square meter, and it has no famous inventor of its own.

Electricians know it best. Wire and cable sizes are given as the cross-sectional area of the copper conductor, and the standard sizes listed for UK domestic wiring are 1, 1.5, 2.5, 4, 6 and 10 mm². Twin and earth cable of 2.5 mm² typically serves sockets on a 16 A radial or 32 A ring circuit, 1 mm² serves lighting on a 6 A breaker, and 4 mm² feeds a cooker or shower. Conductor size depends on current capacity and allowed voltage drop, not on voltage alone. One square inch is exactly 645.16 mm², so small parts in either system compare easily.

1 square millimeter = 0.000001 square meters (exactly).

Sources: Wikipedia: Electrical wiring in the United Kingdom; Wikipedia: Centimetre-gram-second system of units; Wikipedia: Square metre

Related conversions

See all area units.