Feet and Inches Calculator

Divide the top number by 16. One sixteenth is 0.0625, so the scale runs 1/16 = 0.0625, 1/8 = 0.125, 3/16 = 0.1875, 1/4 = 0.25, 5/16 = 0.3125, 3/8 = 0.375, 7/16 = 0.4375, 1/2 = 0.5, and on up to 15/16 = 0.9375. Going the other way, multiply the decimal by 16 and read the numerator: 0.8125 × 16 = 13, so 13/16. The inch fields here step in 0.0625 increments, which means every mark on a standard tape lands on an exact value with no rounding error.

Because feet and inches are base-12, so you borrow 12, not 10. Taking 3 ft 9-1/2 in from 8 ft 6 in trips people up: 6 minus 9-1/2 goes negative, so you borrow a foot and rewrite the top number as 7 ft 18 in. Then 7 ft 18 in minus 3 ft 9-1/2 in = 4 ft 8-1/2 in. Converting to plain inches first removes the borrowing entirely — 102 minus 45.5 = 56.5 inches — and you convert back only at the end. That is exactly the order this calculator works in, so it cannot drop a borrowed foot.

Decimal feet fold the fraction into the foot: 8 ft 6 in is 8.5 ft, and 8 ft 3 in is 8.25 ft. Surveys, site plans, grading drawings, and most spreadsheets use decimal feet, while carpenters, architectural plans, and tape measures use feet and inches. The conversion is inches ÷ 12, so 8 inches is 0.667 ft — not 0.8 ft, which is the single most common estimating mistake. This calculator prints both forms plus meters, so the same measurement can go to a framer and onto a civil drawing without redoing the math.

Yes. The inch fields step in 0.0625 — one sixteenth — and accept anything from 0 up to 11.9375, which is 11-15/16. Type 6.5 for 6-1/2, 4.375 for 4-3/8, or 10.8125 for 10-13/16. If you work in thirty-seconds, type the decimal directly, since 1/32 is 0.03125 and the box accepts values finer than the step. Anything 12 inches or more belongs in the feet field instead, so 14 inches is entered as 1 ft 2 in. Results show four decimal places, finer than any tape can actually be read.

It repeats the answer, which is how most real takeoffs work. If a stair skirt needs 4 ft 7-1/2 in of trim and you have six identical stairways, set the multiplier to 6 and the result is 27 ft 9 in in one step. It works the same way for studs, balusters, deck boards, or any run of matching pieces. Leave it at 1 for plain arithmetic. Note the multiplier applies after the add or subtract — the math is (A + B) × 6, not A + (B × 6) — so group your two measurements accordingly.

Subtracting a larger measurement from a smaller one clamps the result to 0 rather than reporting a negative length, because a negative board or wall is nearly always a data-entry slip rather than a real answer. If you want the gap between the two, just swap them: 3 ft 9-1/2 in taken from 8 ft 6 in and 8 ft 6 in taken from 3 ft 9-1/2 in describe the same 4 ft 8-1/2 in difference. So if you see 0 where you expected a number, check that the bigger measurement is in the first pair of boxes.