How the Feet-Inch Calculator works
This calculator does tape-measure math: it adds, subtracts, multiplies and divides lengths in feet, inches and fractions, like 10' 6" + 4' 2 3/8". The answer shows as feet and inches, inches, decimal feet and meters, rounded to 1/16" or the fraction you pick. Multiply two lengths for square feet, three for cubic feet and cubic yards.
By hand: turn each measurement into inches (feet × 12, plus the inches, plus the fraction as a decimal), do the math, then divide the result by 12. The whole number is feet and the remainder is inches; multiply any leftover decimal by 16 and round to get sixteenths.
Example: 10' 6" + 4' 2 3/8". 10' 6" = 120 + 6 = 126" and 4' 2 3/8" = 48 + 2.375 = 50.375". 126 + 50.375 = 176.375". 176.375 ÷ 12 = 14 with 8.375" left over, so the answer is 14' 8 3/8".
Type a fraction as 3/8 with no spaces and a mixed number as 2 3/8. Use ÷ to divide: 10' 6" in 4 equal parts is 10' 6" ÷ 4 = 2' 7 1/2". Metric works too, so 2.5m + 1' is a valid entry. A number with no ' or " is a plain number, which is how you multiply or divide a length by a count.
Frequently asked questions
How do you add feet and inches?
Add the inches, then the feet, and carry every 12" over as a foot: 5' 8" + 3' 7" = 8' 15" = 9' 3". Add fractions over a common bottom number first: 3/8" + 3/4" = 3/8" + 6/8" = 9/8" = 1 1/8".
How do I turn decimal inches into a fraction?
Multiply the decimal part by 16 and round to a whole number of sixteenths. 16.97": 0.97 × 16 = 15.5, which rounds to 16/16, so 17" to the nearest 1/16" (16 31/32" to the nearest 1/32"). That is how a 12" offset's 45° travel of 12 × 1.414 = 16.97" becomes 17" on the tape.
How do you convert inches to feet and inches?
Divide by 12: the whole number is feet and the remainder is inches. 176 3/8" ÷ 12 = 14 with 8 3/8" left over, so 14' 8 3/8". For decimal feet, divide the inches by 12: 176.375 ÷ 12 = 14.698 ft.
How do you convert decimal feet to feet and inches?
Keep the whole feet and multiply the decimal part by 12 for the inches. 10.75 ft is 10' plus 0.75 × 12 = 9", so 10' 9". Type 10.75' and the calculator shows it in feet and inches.
How do I divide a length into equal parts?
Divide the total by the number of parts: 10' 6" ÷ 4 = 126" ÷ 4 = 31.5" = 2' 7 1/2". For evenly spaced supports with one at each end, divide by the number of spaces, which is one less than the number of supports.