Practical measurement guide
1/2 Inch to MM and CM
Convert 1/2 inch to decimal inches, centimeters, and millimeters with ruler-position and rounding guidance.
1/2 inch equals 0.5 decimal inches, 1.27 cm, and 12.7 mm.
in
Decimals and fractions work, for example 1.5, 1/2, or 1 1/2.
mm
Try a value
Fractions
0.5 in = 12.7 mm
0.5 in × 25.4 = 12.7 mm
Decimal inches0.5 in
Feet + inches0 ft 0.5 in
Nearest 1/16 inch1/2"
Fraction inch result
1/2 inch equals 0.5 inches, 1.27 cm, and 12.7 mm.
Calculation method
First divide 1 by 2 to get decimal inches. Then multiply decimal inches by 25.4 for millimeters or by 2.54 for centimeters.
Nearby ruler fractions
| Fraction | Decimal inches | Millimeters |
|---|---|---|
| 1/2 in | 0.5 | 12.7 mm |
Precision note
This page keeps the fraction exact and rounds the metric result only for display. Use 64ths when the tool or ruler supports fine increments; otherwise round to 32nds, 16ths, or 8ths.
Related measurement tools
Frequently asked questions
What is 1/2 inch as a decimal?
1/2 inch is 0.5 decimal inches.
How many mm is 1/2 inch?
1/2 inch equals 12.7 millimeters.
Is the fraction simplified?
Yes. This page uses a canonical common ruler fraction and does not publish duplicate simplified equivalents.