Adding 5' 10 1/2", 3' 7 3/4" and 2' 1/8" gives 11' 6 3/8" on the feet and inches calculator: 70.5 in + 43.75 in + 24.125 in is 138.375 in, and 138.375 ÷ 12 is 11 feet with 6 3/8 in left over.
How to add feet and inches
Total inches = (feet × 12 + inches + fraction) for each length, added; feet = total ÷ 12, inches = the remainder
Write each measurement the way it reads on the tape: 5' 10 1/2", or 5 ft 10.5 in. The apostrophe is feet, the quote is inches, and a fraction goes after the whole inches with a space, as in 10 1/2. Use the plus and minus button next to a row to add or subtract that length, and add rows for as many values as you have. Rows without a unit are refused, because a bare 10 could be feet or inches.
Feet and inches cannot be added column by column when the inches pass 12. 8' 9" + 5' 6" is 13 ft 15 in, which is 14' 3". The calculator does that carry for you and rounds the answer to the nearest 1/16 in (or 1/8 or 1/32 if you choose).
Subtract feet and inches
Set the row's button to minus. 8' - 3' 7 5/8" = 4' 4 3/8": 96 in - 43.625 in = 52.375 in. If you take away more than you start with the total turns negative and shows a minus sign, which is a quick way to find how far a board is short.
Multiply and divide feet and inches
Divide a length by a number to split it into equal parts: 10' 3" ÷ 4 = 2' 6 3/4" (123 in ÷ 4 = 30.75 in). Multiply by a number to scale it: 5 1/2" × 2 = 11". Multiply two lengths and you get an area: 12' × 10' is 120 sq ft. Divide a length by a length to see how many fit: 10' ÷ 2' is 5.
Feet and inches with fractions
Fractions are exact in the calculation and rounded only in the answer. 1/16 in is 0.0625 in, 1/8 in is 0.125 in and 1/4 in is 0.25 in, so 2' 1/8" is 24.125 in. If the rounding to 1/16 matters for a cut, watch the "Same total in other units" list, which keeps four decimals.
Feet and inches to decimal, meters and centimeters
The convert tab takes a length and writes it as decimal feet, decimal inches, meters, centimeters, millimeters and yards. 5' 10" is 5.8333 ft, 70 in, 1.778 m and 177.8 cm, because one inch is exactly 2.54 cm (NIST Handbook 44). The example total, 11' 6 3/8", is 11.5313 ft or 3.5147 m.
A plain number has no unit, so choose what it means: 5.8333 read as feet becomes 5' 10", and 70 read as inches becomes 5' 10" as well. Typing 178 cm ignores that setting.
| Feet and inches | Decimal feet | Centimeters |
|---|---|---|
| 5' 0" | 5.0 ft | 152.4 cm |
| 5' 6" | 5.5 ft | 167.64 cm |
| 5' 10" | 5.8333 ft | 177.8 cm |
| 6' 0" | 6.0 ft | 182.88 cm |
| 6' 2" | 6.1667 ft | 187.96 cm |
Which tool for which job
Use this page for adding and converting a list of measurements. When you also need pitch, stairs, rafters or a keypad, the construction calculator has them. To turn the total into material, the linear feet calculator counts boards, the square footage calculator handles rooms, and the cubic feet calculator handles volume. Pieces of a known board width convert with the linear feet to square feet calculator. The rest are in measuring and planning calculators.