Convert a length from feet and inches to centimeters, with a quick check that carries extra inches into feet.
Table of contents
How to use our Feet and Inches to Centimeters Converter
- Enter the feet part in Feet (ft), such as 5 for a height of 5 ft 8 in.
- Enter the inch part in Inches (in), such as 8 or 8.5; values like 13 are allowed.
- Choose Show centimeters with (decimal places): 0 for whole-centimeter forms, 1 for most height use, or 2 for a more exact answer.
- Click Calculate and read Centimeters first, then use Nearest whole centimeter if your form needs a whole number.
- Sanity-check the result with Same length in feet and inches and Total inches; for example, 5 ft 13 in should clean up to 6 ft 1 in.
Definitions
Feet (ft): The larger US length unit in the entry. One foot equals 12 inches.
Inches (in): The smaller US length unit in the entry. Extra inches are added to the feet part.
Centimeters (cm): The metric length unit used for the main answer. One inch equals 2.54 centimeters.
Total inches: The feet part changed into inches, plus the inches part you entered.
Same length in feet and inches: A cleaned-up check that turns every 12 inches into 1 foot, so 5 ft 13 in becomes 6 ft 1 in.
Decimal places: The number of digits shown after the decimal point in the centimeter answer.
Common mistakes and quick fixes
Mistake: Leaving Feet (ft) blank when the length has no feet.
Fix: Enter 0 in Feet (ft) and put the full inch amount in Inches (in) .
Mistake: Leaving Inches (in) blank for an even number of feet.
Fix: Enter 0 in Inches (in) so the converter knows there are no extra inches.
Mistake: Typing letters or marks like 5ft in Feet (ft) or 8in in Inches (in) .
Fix: Use numbers only, such as 5 and 8.5.
Mistake: Treating 13 in Inches (in) as an error.
Fix: Keep it if that is what you measured; Same length in feet and inches will carry every 12 inches into 1 foot.
Mistake: Mixing decimal feet in Feet (ft) with extra inches in Inches (in) by accident.
Fix: If you enter 5.5 in Feet (ft) , remember that already includes 6 inches before adding Inches (in) .
Mistake: Choosing the wrong Show centimeters with (decimal places) setting for a form.
Fix: Use 0 decimal places when the form asks for a whole centimeter, or compare with Nearest whole centimeter .
Limitations & Key Assumptions / Boundary Conditions
- The converter treats Feet (ft) and Inches (in) as one combined nonnegative length.
- Inches of 12 or more are valid. They are not blocked because they can describe the same total length.
- Decimal feet and decimal inches are allowed, but using both can be easy to misread. For height, whole feet plus inches is usually clearer.
- The displayed Centimeters value is rounded based on Show centimeters with (decimal places); internal math uses the unrounded value.
- Nearest whole centimeter is rounded from the exact centimeter value, not from the already displayed centimeter value.
- Negative lengths are not supported because this converter is for physical length or height entries.
Methodology
How the conversion is calculated
The converter first changes the feet part to inches, adds the inch part, then multiplies by the exact inch-to-centimeter factor. The foot-to-inch relationship is also exact:
1 foot = 12 inches.
total_inches = feet * 12 + inches
centimeters_exact = total_inches * 2.54
centimeters = round(centimeters_exact, cm_decimals)
nearest_whole_cm = round(centimeters_exact, 0)
For the cleaned-up feet-and-inches check, the converter carries each group of 12 inches into 1 foot.
cleaned_feet = floor(total_inches / 12)
cleaned_inches = total_inches - cleaned_feet * 12
Mini-example
If you enter 5 in Feet (ft) and 13 in Inches (in), the total is 5 * 12 + 13 = 73 inches. Multiplying 73 by 2.54 gives 185.42 centimeters. The cleaned-up check is 6 ft 1 in because 73 inches contains 6 full feet with 1 inch left over.
Rounding
The main Centimeters result uses the selected Show centimeters with (decimal places) setting. The Nearest whole centimeter result is rounded separately from the exact centimeter value, so it stays consistent even when the main answer is shown with 1 or 2 decimal places.