How to use this tool
Enter signed feet and inches for each length to add or subtract.
Use fractions or mixed numbers for inches, with inches below 12. Check the result in both feet/inches and metric.
Total inches = sum[sign × (12×feet + inches)]
Worked example
4 ft 1.5 in · combined length
Fixed example using the settings below. Monetary examples use USD; dates and times use their stated reference values. This example stays unchanged when you edit your calculation.
Example inputs
- Signed lengths: feet, inches: 5, 3 1/2; -1, 2
Method illustration: 5 ft 3½ in minus 1 ft 2 in = 4 ft 1½ in.
Assumptions and limits
- Inches accept whole numbers, fractions and mixed numbers, from 0 to below 12. Decimal feet are not accepted.
Method reference: NIST measurement conversion reference
Check or report a result
Check the units, selected calculation and assumptions first. Compare the fixed example above with your inputs to identify what changed.
Report a calculation issue with the page address, hypothetical inputs, result displayed and result expected. Do not include passwords, bank details or other private information.