Feet and Inches Calculator

Convert each measurement to inches first, add them, then convert back. Multiply the feet by 12, add the inches and any fraction, and you've got total inches. Add all the totals, divide by 12 for the feet, and the remainder is the inches. So 5 ft 9 1/2 in plus 3 ft 4 3/4 in becomes 69.5 + 40.75 = 110.25 inches, which is 9 ft 2 1/4 in. This calculator runs those steps for every row at once, so you don't have to carry fractions in your head.

Same idea in reverse: turn both measurements into total inches, subtract, and convert back to feet and inches. The part people trip on is borrowing, like taking 8 ft 9 in away from 12 ft 3 in, where you can't subtract 9 from 3 directly. Working in total inches sidesteps that completely: 147 - 105 = 42 inches, which is 3 ft 6 in. Switch any row here to minus and it's handled, fractions included.

You can't multiply the feet and inches separately, because 3 x 2 ft 8 in isn't 6 ft 24 in in usable form. Convert to inches, multiply, and convert back: 2 ft 8 in is 32 inches, times 3 is 96 inches, which is 8 ft exactly. That's how you price three boards, six studs, or a doubled trim run. Enter the length once here, set the multiply box, and the total updates instantly.

Divide the inches (including the fraction) by 12 and add that to the feet. So 9 ft 2 1/4 in is 9 + 2.25/12 = 9.1875 decimal feet. Decimal feet show up on engineering plans, surveying gear, and material takeoffs, so it's worth having both forms. This calculator always shows the decimal-feet figure alongside the feet-inch answer, plus total inches and centimeters.

The shortest tick marks on a standard tape are sixteenths of an inch. Count from the last whole inch: the first tiny mark is 1/16, the slightly taller one after it is 1/8 (that's 2/16), the mid-height mark is 1/4, and the tallest between inches is 1/2. Most people just learn the halves, quarters, and eighths, then count one tick up or down for the sixteenths. The fraction chart on this page lists every sixteenth with its decimal and millimeter value.

One inch is exactly 2.54 cm, so convert the whole measurement to inches and multiply. A length of 9 ft 2 1/4 in is 110.25 inches, and 110.25 x 2.54 = 280.04 cm, or about 2.8 meters. The calculator shows the centimeter and meter figures automatically with every result, which helps when a plan, a product spec, or a drawing is metric and your tape isn't.

Because that's the finest mark on a standard tape measure, so a finer fraction isn't something you can actually cut to on site. When you divide a measurement, say a 92 5/8 in board into 3, the exact answer is 30.875 inches and the calculator shows it as 30 7/8 in. When the exact value falls between sixteenths, it rounds to the nearest one and tells you it did, and the decimal figures next to it stay exact so nothing is hidden.