Length converter
Millimeters to centimeters.
Express small metric measurements in centimeters while preserving their millimeter detail.
The marker shows the fractional part of one inch. This diagram illustrates tick positions; it is not a physical-size ruler.
Conversion formula
centimeters = millimeters ÷ 10
Enter the source length above. The result updates immediately. These calculations use exact length definitions: 1 m = 100 cm = 1000 mm, 1 in = 25.4 mm, and 1 ft = 12 in. Only the displayed answer and fractional ruler mark are rounded. The feet-and-inches output splits a length into whole feet and remaining inches; decimal feet do not encode an inch count.
Worked example
85.6 mm equals 8.56 cm. That is the long edge of a standard ID-1 bank card. Notice that a millimeter measurement may already contain a decimal; do not round it to 86 mm before converting unless the intended tolerance allows it.
Conversion table: mm → cm
Select a source value to load it into the calculator. Decimal results are displayed to at most six places; inch fractions in this table are rounded to 1/16 inch.
| Millimeters (mm) | Centimeters (cm) | Nearest inch fraction |
|---|---|---|
| 0.1 | ≈ 1/16 in | |
| 0.5 | ≈ 3/16 in | |
| 1 | ≈ 3/8 in | |
| 1.5 | ≈ 9/16 in | |
| 2 | ≈ 13/16 in | |
| 2.5 | ≈ 1 in | |
| 5 | ≈ 1 15/16 in | |
| 5.398 | ≈ 2 1/8 in | |
| 7 | ≈ 2 3/4 in | |
| 8.56 | ≈ 3 3/8 in | |
| 10 | ≈ 3 15/16 in | |
| 30 | ≈ 11 13/16 in |
When to use this conversion
Use this for dimensions of small objects, packaging, printed layouts, and a clearer centimeter reading from a fine millimeter scale. Converting the unit does not change how accurately the object was measured.
10 mm is 1 cm; 100 mm is 10 cm. Divide by ten, not one hundred. The latter would convert millimeters into decimeters.
Exact conversion versus a ruler reading
The unit relationship is exact, but a measured object may have uncertainty. At 1/16 inch, the maximum rounding difference is half a tick: 1/32 inch, or 0.79375 mm. The calculator shows the actual rounding difference for your value. Use a finer division only if the source measurement and physical instrument support that precision.
Next steps
Numerical conversion needs no display calibration. Comparing a physical object against your screen does. Use the ruler for small objects, a verified paper ruler away from your display, or an appropriate calibrated instrument for safety-critical measurements.
Related converters
Reference: NIST unit conversion factors. Calculations use the international foot, not historical survey-foot units. Fractions are explicitly approximate. NIST ↗