Convert Millimeter to Centimeter (mm → cm)

Converting millimeters to centimeters is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in millimeters

   Start with the number of millimeters (mm) you want to convert.
2. 2
   Multiply by 0.1

   The conversion factor from mm to cm is 0.1. Multiply your value by this number.
3. 3
   Read the result in centimeters

   The result is your value in centimeters (cm).

Multiply the value in millimeters by 0.1. For the reverse direction, multiply by 10.

• ✓1 mm is the smallest graduation on a standard ruler. 10 mm = 1 cm exactly.
• ✓Rainfall in mm is depth — 25 mm of rain over 1 m² equals 25 litres of water.
• ✓For very small measurements switch to micrometres (µm) — 1 mm = 1000 µm.

• ✗Reading an engineering drawing dimensioned in mm as if it were cm — a factor-of-10 error.
• ✗Using 25 instead of 25.4 when converting mm to inches — the error matters in CNC machining.
• ✗Confusing millimetre (length) with millilitre (volume) — both abbreviated with "ml" but on different scales.

What is the Millimeter?

The millimeter equals one thousandth of a meter (0.001 m) and is the precision unit of choice in engineering, manufacturing, electronics, and meteorology. Its small size makes it ideal for tolerances in mechanical parts, paper thickness, and rainfall measurements. A standard credit card is 0.76 mm thick, and a sheet of office paper is about 0.1 mm. The millimeter is the universal unit for tire-tread depth, weather-station rainfall reports, and 3D printer resolution. It relates to the centimeter (10 mm = 1 cm), the inch (25.4 mm = 1 in exactly), and the micrometer (1 mm = 1,000 µm). Engineering drawings worldwide default to millimeters for dimensions, except in the United States where inches remain dominant in mechanical engineering.

• Rainfall measurements in weather reports
• Precision engineering and manufacturing tolerances
• Medical imaging — tumor and wound size

What is the Centimeter?

The centimeter equals one hundredth of a meter (0.01 m) and is the everyday metric unit for body measurements, clothing, furniture, and household items. It bridges the gap between the meter (too large for personal items) and the millimeter (too small for clothing). The centimeter is widely used in countries with metric systems for height (a person is 160–185 cm tall), paper sizes (A4 is 21 × 29.7 cm), and medical measurements. Although not strictly an SI base unit, it is one of the most common units in daily metric usage. The centimeter relates to the inch (1 cm ≈ 0.394 in) and to the millimeter (1 cm = 10 mm). It became standard with the metric system's adoption across continental Europe in the 19th century.

• Height and body measurements in medical records
• Ready-to-wear clothing sizes in Europe and Asia
• Furniture and interior design dimensions