One centimeter is exactly 10 millimeters. Multiply centimeters by 10, or move the decimal point one place right. 0.75 cm is 7.5 mm; 1.75 cm is 17.5 mm.
Why it is exactly 10
A centimeter is a hundredth of a meter and a millimeter a thousandth, so a centimeter contains exactly ten millimeters. Both are defined against the meter by powers of ten, which makes this the simplest conversion in the metric system — one decimal place, no arithmetic.
Common values
| Centimeters | Millimeters |
|---|---|
| 0.1 cm | 1 mm |
| 0.25 cm | 2.5 mm |
| 0.5 cm | 5 mm |
| 0.75 cm | 7.5 mm |
| 1 cm | 10 mm |
| 1.5 cm | 15 mm |
| 1.75 cm | 17.5 mm |
| 2.5 cm | 25 mm |
| 5 cm | 50 mm |
| 7.5 cm | 75 mm |
| 10 cm | 100 mm |
Which unit should you use?
Centimeters suit human-scale description — height, clothing, furniture. Millimeters suit anything where precision matters, because they avoid decimals: 1.75 cm and 17.5 mm are the same length, but the second is harder to misread and is what an engineering drawing will show.
A useful physical anchor: a standard credit card is 85.6 mm long and 53.98 mm tall, so its short edge is almost exactly 54 mm or 5.4 cm.
Common mistake
Confusing this with the meter conversion and shifting two places instead of one. 1.75 cm is 17.5 mm, not 175 mm — 175 mm would be 17.5 cm. The check that never fails: millimeters are smaller, so the number must get bigger, but only by a factor of ten.
Centimeters to millimeters is a simple ×10: 4.5 cm = 45 mm, 0.75 cm = 7.5 mm. Rulers show both scales side by side, but manufacturing, dentistry, jewellery and rainfall all quote millimeters, while clothing, body measurements and school maths use centimeters.
Where you'll meet this conversion
- A 1.5 cm hem allowance is 15 mm on the pattern.
- A ring inner diameter of 1.75 cm is 17.5 mm — roughly a US size 7.
- A phone that is 0.8 cm thick is 8 mm.
Common mistake
Multiplying by 100 (that is meters to centimeters). Between cm and mm the factor is only 10, so the number should barely change in size — just gain one digit.
Quick answer: one centimeter equals 10 millimeters. So to convert centimeters to millimeters, multiply by 10.
How to convert centimeters to millimeters
millimeters = centimeters × 10
The centimeter, one hundredth of a meter, is the everyday small unit of the metric world: body height, clothing measurements and school rulers all speak in centimeters.
The millimeter is one thousandth of a meter and the workhorse of precision measurement — engineering drawings, 3D printing tolerances and rainfall totals are all quoted in millimeters.
Centimeter to Millimeter conversion table
| Centimeter (cm) | Millimeter (mm) |
|---|---|
| 0.01 cm | 0.1 mm |
| 0.1 cm | 1 mm |
| 0.25 cm | 2.5 mm |
| 0.4 cm | 4 mm |
| 0.75 cm | 7.5 mm |
| 1.25 cm | 12.5 mm |
| 1.75 cm | 17.5 mm |
| 2.5 cm | 25 mm |
| 3.5 cm | 35 mm |
| 4.5 cm | 45 mm |
| 6 cm | 60 mm |
| 8 cm | 80 mm |
| 10 cm | 100 mm |
| 12 cm | 120 mm |
| 14 cm | 140 mm |
| 16 cm | 160 mm |
| 18 cm | 180 mm |
| 20 cm | 200 mm |
| 24 cm | 240 mm |
| 26 cm | 260 mm |
| 30 cm | 300 mm |
| 35 cm | 350 mm |
| 45 cm | 450 mm |
| 55 cm | 550 mm |
| 65 cm | 650 mm |
| 75 cm | 750 mm |
| 85 cm | 850 mm |
| 95 cm | 950 mm |
| 110 cm | 1,100 mm |
| 125 cm | 1,250 mm |
| 175 cm | 1,750 mm |
| 250 cm | 2,500 mm |
| 350 cm | 3,500 mm |
| 450 cm | 4,500 mm |
| 600 cm | 6,000 mm |
| 750 cm | 7,500 mm |
| 900 cm | 9,000 mm |
| 1,500 cm | 15,000 mm |
| 2,500 cm | 25,000 mm |
| 10,000 cm | 100,000 mm |
Need the opposite direction? Use the Millimeter to Centimeter converter, or read our complete guide to length conversions for every formula in one place.
Frequently asked questions
How many millimeters are in one centimeter?
One centimeter equals 10 millimeters. Multiply any centimeter value by 10 to get millimeters.
What is 10 centimeters in millimeters?
10 centimeters equal 100 millimeters (10 × 10).
Is the centimeter to millimeter conversion exact?
The conversion factor used here (10) is based on the internationally agreed definitions of both units, so results are exact up to rounding of the final decimal places.
Is my data stored when I use this converter?
No. The conversion runs entirely in your browser with JavaScript — nothing you type is sent to a server, logged or stored.