Clad
Feet and inches calculator: add, convert and find square feet
Working in feet, inches and fractions is easy to get wrong in your head. These are the rules and a few examples, so you can check a tape reading or a plan dimension.
How do you add feet and inches?
Add the feet, add the inches and fractions, then carry: every 12 inches becomes one foot.
Example. 10 ft 3 1/2 in + 4 ft 9 3/8 in. Inches: 3 1/2 + 9 3/8 = 12 7/8, which is 1 ft 0 7/8 in. Feet: 10 + 4 + 1 = 15. The answer is 15 ft 0 7/8 in.
How do you convert inches to feet?
Divide by 12. The whole part is the feet and the remainder is the inches.
Example. 100 in ÷ 12 = 8.333 ft, or 8 ft 4 in.
Feet and inches to decimal feet
Divide the inches by 12 and add the feet.
Example. 7 ft 9 in = 7 + 9 ÷ 12 = 7.75 ft.
Feet and inches to square feet
Turn both lengths into decimal feet, then multiply.
Example. A room 12 ft 6 in by 8 ft 3 in: 12.5 × 8.25 = 103.125 sq ft.
Reading a tape in sixteenths
A tape marks 1/16 in. Each sixteenth is 0.0625 in, so 3/8 in is 6/16 and 0.375 in. Keep a result in sixteenths unless the plan asks for decimals, and note when you round.
Feet and inches in Clad
Clad is a calculator you type into the way you read the tape: feet, inches and fractions. It adds them exactly and rounds once, and every result names its rounding, so a number never changes without you seeing it. It also shows the result in decimal inches, decimal feet, millimetres, centimetres or metres, and keeps every sum on a tape you can add up and export.
See what Clad does. Clad is coming soon to the iPhone.
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How this page was made
Written with the help of an AI assistant (Claude, by Anthropic). Every worked example was computed again by a program and checked against its formula. Building codes differ by place: check yours before you build.