GUIDE · 2026-07-23
How to use the Feet and Inches Calculator
Feet-and-inches notation mixes base-12 length with binary fractions, so treating each part as a decimal produces mistakes. The tool converts everything to decimal inches, calculates, then formats the result to a common 1/16 inch.
How it works
Total inches = feet×12 + inches + fractional inches
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Step-by-step
- 01Enter the first length, for example 5' 7 3/8".
- 02Choose convert, add or subtract and enter a second measurement when needed.
- 03Compare feet and inches, total inches, decimal feet and metric results.
Worked example
INPUT5 ft 7 3/8 in
RESULT67.375 in = 5.614583 ft = 171.133 cm
The displayed fraction rounds to 1/16 inch while arithmetic retains decimal inches.Limits and checks
- Account separately for saw kerf and the tolerance required by the project.
- For subtraction, put the longer physical measurement first.
Useful examples
- Add lumber cut lengths
- Compare furniture and room measurements
- Convert fractional inches to metric
Frequently asked questions
Which formats can I enter?
Use 5 ft 7 in, 5' 7 3/8", 67.375 in or decimal feet.
How are fractions rounded?
The display rounds to the nearest 1/16 inch while calculations retain decimal inches.
Can a length be negative?
Physical input lengths must be nonnegative. If subtraction is negative, reverse the operands.