The one number to remember
One inch is exactly 2.54 centimeters. The National Institute of Standards and Technology (NIST) explains that the inch, derived from the yard as defined effective July 1, 1959, is exactly 25.4 millimeters, which is the same as 2.54 centimeters. One foot is 12 inches, or 30.48 centimeters.
Feet and inches to centimeters
Change the feet to inches, add the remaining inches, then multiply by 2.54.
Example: 5′10″ is 5 × 12 + 10 = 70 inches. Then 70 × 2.54 = 177.8 cm.
Centimeters to feet and inches
Divide the centimeters by 2.54 to get total inches. Divide that by 12 for whole feet, and the remainder is the inches.
Example: 170 cm ÷ 2.54 = 66.93 inches. That is 5 feet (60 inches) with 6.93 inches left, which rounds to 5′7″.
Rounding conventions vary. Many forms round to the nearest inch, while medical and sports records often keep one decimal. Keep the extra digits until the final step, and round only once.
Common mistakes
Most conversion errors come from mixing decimal feet with feet and inches. A decimal foot divides one foot into tenths, while an inch divides it into twelfths.
- 5.5 feet is 5 feet and 6 inches (0.5 × 12), so it is 5′6″, not 5′5″.
- 5.10 feet is not 5′10″. It is 5 feet and 1.2 inches.
- Do not treat the inch mark as a decimal. 5′7″ is 67 inches, not 5.7 feet.
- Rounding 2.54 to 2.5 adds up. At 70 inches the result is off by 2.8 cm.
Using the tool
The height comparison tool accepts feet and inches or centimeters, so you can type whichever you know. It draws the figures to scale from the values you enter. If a number looks wrong on screen, check which unit you entered before assuming the drawing is off.
Sources and further reading
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