Convert Square centimetres to Square millimetres
1 square centimetre is 100 mm². One square centimetre is exactly 100 square millimetres.
One square centimetre is 100 square millimetres. To convert square centimetres to square millimetres, multiply by 100; to go the other way, divide by 100 or multiply by 0.01. The factor is exact rather than rounded: it follows from NIST Office of Weights and Measures. A ten-thousandth of a square metre — not a hundredth, which is the mistake squaring a prefix invites.
Factor checked against the defining standard · How we check
- Square centimetres × 100
1 * 100100 mm²
1 square centimetre in every area unit
| Unit | Value | Exact factor |
|---|---|---|
| square inches | 0.15500031 sq in | × 0.155000310001 |
| square feet | 0.001076391042 sq ft | × 0.00107639104167 |
| square yards | 0.0001195990046 sq yd | × 0.00011959900463 |
| acres | 0.00000002471053815 ac | × 0.0000000247105381467 |
| square meters | 0.0001 m² | × 0.0001 |
| square millimetres | 100 mm² | × 100 |
| square centimetres (as entered) | 1 cm² | — |
| square kilometres | 0.0000000001 km² | × 0.0000000001 |
| square miles | 0.00000000003861021585 mi² | × 0.0000000000386102158542 |
| hectares | 0.00000001 ha | × 0.00000001 |
Factors are entered by hand from NIST Office of Weights and Measures rather than derived from a units library, so the ones that terminate are exact rather than rounded.
The same converter answers this pair however it is written: sqcm to sqmm is how the symbols are typed on a keyboard with no superscript on it.
How do you convert square centimetres to square millimetres? The converter and the working
- 1.Take the measurement in square centimetres.
- 2.Multiply by 100 — that is how many square millimetres fit in one square centimetre.
- 3.To go back the other way, divide by 100, or multiply by 0.01.
Worked example: 25 square centimetres to square millimetres
- Formula
- cm² × 100 = mm²
- Arithmetic
- 25 × 100 = 2,500 mm²
- Answer
- 25 cm² = 2,500 mm²
The factor is exact, so this figure is exact too — only the display is rounded.
Square centimetres to square millimetres conversion table
| Square centimetres | Square millimetres |
|---|---|
| 1 cm² | 100 mm² |
| 2 cm² | 200 mm² |
| 3 cm² | 300 mm² |
| 4 cm² | 400 mm² |
| 5 cm² | 500 mm² |
| 6 cm² | 600 mm² |
| 7 cm² | 700 mm² |
| 8 cm² | 800 mm² |
| 9 cm² | 900 mm² |
| 10 cm² | 1,000 mm² |
| 12 cm² | 1,200 mm² |
| 15 cm² | 1,500 mm² |
| 20 cm² | 2,000 mm² |
| 25 cm² | 2,500 mm² |
| 50 cm² | 5,000 mm² |
| 100 cm² | 10,000 mm² |
| 200 cm² | 20,000 mm² |
| 300 cm² | 30,000 mm² |
| 500 cm² | 50,000 mm² |
| 1000 cm² | 100,000 mm² |
| 2000 cm² | 200,000 mm² |
| 5000 cm² | 500,000 mm² |
| 10000 cm² | 1,000,000 mm² |
What is a square centimetre?
A ten-thousandth of a square metre — not a hundredth, which is the mistake squaring a prefix invites. 10,000 cm² to the square metre.
What is a square millimetre?
A millionth of a square metre, because the millimetre is a thousandth of a metre and area squares the factor. The working unit of engineering drawings and of cable cross-sections.
How many square millimetres are in a square centimetre?
One square centimetre is 100 square millimetres, exactly. Going the other way, one square millimetre is 0.01 square centimetres. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every area unit here
The whole group — 10 units with their symbols and the size of each one in square meters — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to a square centimetre.
Cite this page
- APA
- Rule Calculator. (2026). Convert Square centimetres to square millimetres. Rule Calculator. https://rulecalculators.com/convert/square-centimeter-to-square-millimeter
- MLA
- "Convert Square centimetres to square millimetres." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/square-centimeter-to-square-millimeter.
- Chicago
- Rule Calculator. "Convert Square centimetres to square millimetres." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/square-centimeter-to-square-millimeter.
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Questions people actually ask
- How many square millimetres are in a square centimetre?
- 100. A millionth of a square metre, because the millimetre is a thousandth of a metre and area squares the factor. The working unit of engineering drawings and of cable cross-sections.
- How do I convert square millimetres back to square centimetres?
- Divide by 100, or multiply by 0.01 — they are the same operation.
Other area conversions
Square millimetres to square centimetres — the same conversion the other way.