How this calculator works
Enter a height in feet and inches, or in centimeters, and pick the direction you want to convert. The calculator converts feet and inches to a single total-inches figure, then applies the exact 2.54 cm-per-inch constant to get centimeters, or runs that process in reverse.
The formula
cm = (feet x 12 + inches) x 2.54 Inverse: totalInches = cm / 2.54 feet = floor(totalInches / 12) inches = totalInches - feet x 12 (rounded to the nearest 0.1 in)
Worked example
Converting 5 ft 7 in to centimeters:
- Total inches: 5 x 12 + 7 = 67 in
- Centimeters: 67 x 2.54 = 170.18 cm
Frequently asked questions (FAQ)
How many centimeters are in one inch?
Exactly 2.54 centimeters. This is the international inch definition set by the 1959 yard-and-pound agreement and used consistently across the United States, United Kingdom, Canada, and Australia, so it's the value this calculator uses for every conversion.
Why does this calculator use 2.54 cm exactly instead of a rounded value?
Rounding the constant itself (say, to 2.5) would introduce error that compounds across a whole height, especially for taller people. Using the exact 2.54 cm figure and only rounding the final displayed result keeps the answer as accurate as the input allows.
How do I convert my height from feet and inches to centimeters by hand?
Multiply the feet by 12 and add the inches to get your total height in inches. Then multiply that total by 2.54 to get centimeters. For example, 5 ft 7 in is 67 inches, and 67 x 2.54 is 170.18 cm.
Why might my height in cm not convert back to a round number of inches?
Not every centimeter value divides evenly by 2.54. When it doesn't, the leftover inches are rounded to the nearest tenth for display, so converting back and forth can shift by a fraction of an inch. The underlying math is still exact.
What is the difference between an international inch and other historical inch definitions?
Before 1959, the US and UK used slightly different inch lengths for surveying purposes. The 1959 international agreement standardized 1 inch to exactly 2.54 cm worldwide for everyday and scientific use, which is the definition this calculator applies.
Can I use this calculator for measuring things other than height?
Yes. The math is a straightforward length conversion between feet/inches and centimeters, so it works for any measurement in that range, not just human height, as long as the value fits within the input limits above.