Feet & Inches Calculator (fractions ⇄ metric)
Add, subtract and convert feet and inches with fractions, and switch to centimetres or metres — in your browser.
🔒 Runs entirely in your browser. Your input and output are never sent to a server or stored — fully private.
Add, subtract and convert lengths in feet and inches — including fractions like 3 1/2". Results show both feet-inches and metric.
Add / subtract
Metric → feet & inches
Type lengths like 5’ 3 1/2”, 5ft 3in or 63.5. Click any result to copy.
About this tool
This feet and inches calculator lets you add, subtract, multiply and divide measurements written in feet, inches and fractions of an inch, then read the answer in feet-inches or switch it to centimetres or metres. It is built for woodworking, construction and DIY, where dimensions are rarely whole numbers. Everything is worked out in your browser as you type.
Frequently asked questions
How do I enter a fraction like 3/8 inch?
Type the whole inches and the fraction together, for example 5 and 3/8. The calculator understands common denominators from halves down to sixteenths and thirty-seconds, and it keeps the fraction exact instead of rounding it to a messy decimal.
How accurate is the metric conversion?
Conversions use the international definition of one inch as exactly 25.4 millimetres, so the metric result is mathematically exact. The figure on screen is simply rounded for readability, and you can show more decimal places when a job needs extra precision.
Are the numbers I enter sent to a server?
No. The calculator does all the arithmetic locally in your browser, so the measurements you enter are never uploaded to or stored on a server.