cm² to mm² Converter

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Convert square centimeters to square millimeters using the squared SI relation: 1 cm² = 100 mm² (not 10). So 5 cm² = 500 mm², 25 cm² = 2,500 mm². Practical for fine engineering cross-section work where component sizes are tracked in cm² but tolerance specs are in mm². Browser-local.

Square centimeter (cm²)
Square millimeter (mm²)

Square centimeter (cm²) → Square millimeter (mm²)

Quick reference table

Square centimeter (cm²)Square millimeter (mm²)
1 cm²100 mm²
2 cm²200 mm²
5 cm²500 mm²
10 cm²1000 mm²
25 cm²2500 mm²
50 cm²5000 mm²
100 cm²10000 mm²

Glossary

Square centimeter (cm²)

A square centimeter equals 100 mm² or 10⁻⁴ m². Used for cross-section areas in physics and chemistry, small object surfaces and packaging. Note that 1 m² = 10,000 cm² (not 100), because area scales as the square of the linear dimension. A standard credit card has an area of about 46 cm².

Square millimeter (mm²)

A square millimeter is the area of a square one millimeter on each side, equal to one millionth of a square meter (1 mm² = 10⁻⁶ m²). Used for cross-section areas of wires, fine engineering tolerances, microelectronics and printed circuit board pad sizes. 100 mm² fit into 1 cm², not 10 — area scales as the square of length.

Metric / SI area

In the metric system, area is reported in square meters (SI base) and its scaled units — square millimeter, square centimeter, square kilometer — plus the convenient hectare (10,000 m²) for land. Each step is exactly 100× the previous because area scales as the square of length: 1 m² = 100 dm² = 10,000 cm² = 1,000,000 mm². This squared scaling is the most common manual-conversion error.

Imperial / US Customary area

US customary and UK imperial systems use square inch, square foot, square yard, acre and square mile (144 in² = 1 ft², 9 ft² = 1 yd², 4,840 yd² = 1 acre, 640 acres = 1 mi²). The acre — historically the area a team of oxen could plow in a day — survives as the standard land-parcel unit in the US. Linked to metric by 1 ft² = 0.09290304 m² exactly.

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Square Millimeters to Square Centimeters
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