When you need this conversion
US measurements meeting metric forms: a TV size, a waist measurement, a 27-inch monitor, a suitcase listed in inches for an airline that publishes limits in cm. Sewing patterns and hardware also mix the two.
Quick reference
- ¼ in = 0.635 cm
- ½ in = 1.27 cm
- 1 in = 2.54 cm
- 6 in = 15.24 cm
- 12 in = 30.48 cm
- 36 in = 91.44 cm
Fractions of an inch
US rulers and tape measures use halves, quarters, eighths and sixteenths. Convert the fraction to a decimal first (3/8 = 0.375), then multiply by 2.54: 0.375 × 2.54 = 0.9525 cm.
Common mistakes
Mixing up inches and feet. 6 ft is 72 inches (182.88 cm), not 6 × 2.54.
Rounding 2.54 to 2.5. On 60 inches, that loses 2.4 cm.
For heights, use feet and inches to cm. For the reverse, use cm to inches.