Centimeters to Millimeters (cm to mm)
One centimeter is exactly 10 millimeters. Type either unit and watch the decimal point move.
2.5 cm25 mm
From cm to mm in One Step
Multiply centimeters by 10 to get millimeters. Divide by 10 to come back. Since both are metric, that's the entire conversion: the digits stay put and the decimal point slides one place.
Worked example
A 2.5 cm wood screw is 25 mm, the length printed on the box when the hardware store switches units on you. A 0.8 cm tile gap is 8 mm of grout line.
Where each unit shows up
Millimeters dominate anywhere precision matters: 3D printer beds, drill bits, camera lens threads, plumbing fittings. Centimeters take over for body measurements, sewing patterns and furniture. Same lengths, different habits, and switching between them is why this page exists.
Going further
Crossing into imperial takes real arithmetic, so the cm to inches converter handles that with the exact 2.54 factor.