Centimeters to Millimeters Converter
Enter the length in centimeters below to convert it to millimeters.
Convert Centimeters to Millimeters
Enter a value in centimeters (cm) to convert to millimeters (mm).
Centimeters to Millimeters Conversion Chart (1–40 Continuous)
Continuous 1 to 40 centimeters lookup table with exact decimals and reduced nearest 1/64 fractions. Highlighted rows mark common shop and ruler values.
| Centimeters (cm) | Decimal (mm) | Fraction — Nearest 1/64 (Reduced) | Nearest 1/16 (Tape) |
|---|---|---|---|
1 cm★ Common | 10 mm | 10 mm | 10 mm |
2 cm★ Common | 20 mm | 20 mm | 20 mm |
3 cm★ Common | 30 mm | 30 mm | 30 mm |
4 cm | 40 mm | 40 mm | 40 mm |
5 cm★ Common | 50 mm | 50 mm | 50 mm |
6 cm★ Common | 60 mm | 60 mm | 60 mm |
7 cm | 70 mm | 70 mm | 70 mm |
8 cm★ Common | 80 mm | 80 mm | 80 mm |
9 cm | 90 mm | 90 mm | 90 mm |
10 cm★ Common | 100 mm | 100 mm | 100 mm |
11 cm | 110 mm | 110 mm | 110 mm |
12 cm★ Common | 120 mm | 120 mm | 120 mm |
How to Convert Centimeters to Millimeters
To convert centimeters to millimeters, multiply the length by the following conversion ratio: 10 millimeters/centimeter.
Since one centimeter is equal to 10 millimeters, you can use this simple formula to convert:
The length in millimeters is equal to the length in centimeters multiplied by 10.
For example, here's how to convert 15 centimeters to millimeters using the formula above.
How Many Millimeters Are in a Centimeter?
There are 10 millimeters in a centimeter, which is why we use this value in the formula above.
Our centimeter fraction and decimal calculator can convert centimeters and millimeters, and it automatically converts the results to US customary, imperial, and SI metric values.
Centimeters and millimeters are both units used to measure length. Keep reading to learn more about each unit.
How to Convert Centimeters to Fractional Inches (1/16″, 1/32″ & 1/64″)
Plain-language method for turning decimal inches into a standard tape-measure or machinist ruler fraction
Calculators give you a decimal number (such as 5.905512 in), but tape measures and woodworking rulers are marked in binary fractions of an inch—most commonly 1/16″ on carpenter tapes, 1/32″ on fine woodworking rules, and 1/64″ on machinist scales.
Here is the step-by-step worked example for converting 15 centimeters (cm) into fractional inches:
- Find the decimal inches result: Convert 15 cm to inches to get 5.905512 in.
- Separate the whole inches from the decimal part: Keep the whole number 5 aside, leaving the decimal remainder 0.905512.
- Multiply the decimal part by your desired fraction denominator (16, 32, or 64) and round half up: Multiply 0.905512 by 16, 32, or 64, then round to the nearest whole number (values ending in .5 round up).
- Reduce the fraction to lowest terms: If the rounded top number (numerator) is even, divide both top and bottom by 2 (or their Greatest Common Divisor) until the top number is odd, then combine with your whole inches.
What Is a Centimeter?
A centimeter is a metric unit of length equal to one-hundredth (1/100) of a meter, which is the International System of Units (SI) base unit of length. One centimeter is also equal to 10 millimeters or approximately 0.39370079 inches. [1]
The centimeter, or centimetre, is part of the SI metric system used worldwide for everyday, scientific, and clinical measurements. Centimeters can be abbreviated as cm; for example, 1 centimeter can be written as 1 cm.
In the metric system, "centi" is the Latin-derived prefix for hundredths, or 10⁻². Because 1 international inch is legally defined as 2.54 centimeters, converting between centimeters and inches is anchored by an exact mathematical constant.
Centimeters are measured using metric rulers, tailor's measuring tapes, stadiometers (for human height), and vernier calipers across carpentry, apparel sizing, school science, and medical charts.
What Is a Millimeter?
A millimeter is a metric unit of length equal to one-thousandth (1/1,000) of a meter or one-tenth (1/10) of a centimeter. By international definition, there are exactly 25.4 millimeters in one inch. [2]
The millimeter, or millimetre, is a standard SI metric unit of length. Millimeters can be abbreviated as mm; for example, 1 millimeter can be written as 1 mm.
In the metric system, "milli" is the prefix for thousandths, or 10⁻³. Millimeters are the default unit on mechanical engineering drawings and architectural blueprints worldwide.
Millimeters are commonly measured using metric steel rules, digital vernier calipers, depth gauges, and micrometers in CNC machining, 3D printing, automotive fasteners, and precision manufacturing.
When converting length between centimeters (cm) and millimeters (mm), keep full floating-point precision (1 cm = 10 mm; 1 mm = 0.1 cm) during intermediate calculations and round only the final millimeter figure to match your instrument tolerance.
More Centimeter & Millimeter Conversions
Need to calculate in the opposite direction? Use our millimeters to centimeters converter (mm to cm) to switch your starting unit immediately. You can also explore related tools such as converting inches to millimeters, converting micrometers to millimeters, or converting centimeters to inches.
Convert from Centimeters
Frequently Asked Questions
References
- [1]NIST OWM StandardNIST OWM (SI Units — Length)·Length Metrology Standard — Centimeters (cm) to Millimeters (mm)
- [2]BIPM SpecificationBIPM (SI Base Unit: Metre (m))·Unit Specifications: Centimeter (cm) & Millimeter (mm)
- [3]NIST HB 133 ReferenceNIST HB 133 (NIST Handbook 133 (2019 Ed.))·Conversion Factors & Mathematical Basis (cm to mm)