How the Feet-Inch Calculator works
This calculator does tape-measure math: it adds, subtracts, multiplies and divides lengths written in feet, inches and fractions, like 10' 6" + 4' 2 3/8". Multiply two lengths and you get an area in square feet; multiply three and you get a volume in cubic feet and cubic yards.
To do it by hand, turn every measurement into inches (feet × 12, plus the inches, plus the fraction as a decimal), do the math, then turn the answer back: divide by 12, the whole number is feet and the remainder is inches. Round what is left to the nearest 1/16" (or 1/8" or 1/32", set under "Round to").
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 feet with 8.375" left over, so the answer is 14' 8 3/8" (14.6979 decimal feet, 4.4799 m).
Type a fraction as 3/8 with no spaces, and a mixed number as 2 3/8. Use ÷ to divide: a 10' 6" wall split into 4 equal spaces is 10' 6" ÷ 4 = 2' 7 1/2". Metric works too, so 2.5m + 1' is a valid entry. Press = to keep a calculation on the tape, and tap a tape line to use its answer again.
Fraction to Decimal Chart: common sizes at a glanceInches to Feet Chart: common sizes at a glancemm to Inches Chart: common sizes at a glanceFrequently asked questions
How do you add feet and inches?
Add the inches first, then the feet. If the inches come to 12 or more, carry 12" over as 1 foot: 5' 8" + 3' 7" = 8' 15" = 9' 3". Add fractions the same way first (3/8" + 3/4" = 3/8" + 6/8" = 9/8" = 1 1/8").
How do you convert inches to feet and inches?
Divide by 12: the whole number is feet and the remainder is inches. For example, 176 3/8" ÷ 12 = 14 with 8 3/8" left over, so 14' 8 3/8". For decimal feet, just divide the inches by 12 (176.375 ÷ 12 = 14.6979 ft).
How do you convert decimal feet to feet and inches?
Keep the whole feet and multiply the decimal part by 12 to get the inches. 10.75 ft is 10' plus 0.75 × 12 = 9", so 10' 9". Type 10.75' into the calculator and it shows feet and inches, inches and meters.
How do I get square feet from feet and inches?
Multiply the length by the width. 12' 6" × 10' 4" is 12.5 ft × 10.333 ft = 129.17 sq ft (14.35 sq yd). Multiply two lengths in the calculator and it shows square feet, square yards and square meters for you.
How do I figure cubic yards for a slab?
Multiply length × width × thickness, all as lengths: 12' × 10' × 4" = 40 cu ft. Divide by 27 to get cubic yards: 40 ÷ 27 = 1.481 cu yd. Order a little extra for waste and an uneven subgrade.