SettingsSettings for this calculationUS
The whole feet of the first measurement. Leave it at 0 for a length under a foot.
Read the feet off the tape exactly as it shows them: a reading of 8 ft 3 1/2 in is 8 here, 3 in the inches box, and 1 over 2 for the fraction. Tapes that count inches all the way along print a foot marker every twelve inches, so a reading of 99 1/2 in can go in as 0 ft and 99 in just as well; the page carries every twelve inches into a foot either way. The whole reading can also be typed here with its marks, 8' 3 1/2", which is read as feet and a decimal of a foot; leave the inches and the fraction at 0 if you do.
Tools needed: Tape measure
The whole inches after the feet. Twelve or more is carried into feet for you.
Usually 0 to 11. A fraction can be typed straight into this box as well, written 3 1/2, 3-1/2 or with the inch mark, 3 1/2", and the box shows it as a decimal once you move on; set the fraction's top number to 0 if you do, or the two are added together.
How many of the divisions below sit past the last whole inch: 7 for seven sixteenths, 0 for none.
Count the small marks past the last numbered inch, in the smallest division the blade is marked in, and enter the count here with that division as the bottom number. It does not have to be in lowest terms: 8 over 16 and 1 over 2 are the same half inch.
The division the fraction is counted in: halves, quarters, eighths, sixteenths, thirty-seconds or sixty-fourths.
On a tape marked in sixteenths, the longest mark between two inches is the half, the next longest the quarters, then the eighths, and the shortest the sixteenths. Thirty-seconds are printed on fine rules and on the first foot of some tapes, sixty-fourths on machinist rules.
A second measurement to add or take away, or a number such as a count of pieces to multiply or divide by.
Two lengths can be added or subtracted, and the answer is a length. A length can be multiplied by a count, six studs of the same length, or divided into equal parts, a board shared into three, and the answer is again a length. Multiplying two lengths together would give an area, which is a different calculator's job.
Add the two lengths, or take the second away from the first.
Subtracting takes the second length from the first, in that order. When the second is the longer of the two, the answer comes back with a minus sign and is the amount by which the first falls short.
The whole feet of the length being added or taken away.
Typed the same way as the first: whole feet here, whole inches next, then the fraction as a count over a division. A length under a foot keeps 0 here.
Tools needed: Tape measure
The whole inches of the second length, after its feet.
A typed fraction such as 8 3/4 or 8 3/4" is read here too. Set the fraction's top number beside it to 0 when you type one, so the fraction is not counted twice.
The count of divisions past the second length's last whole inch: 3 for three quarters.
Counted the same way as the first length's, over whichever division the second length was read in.
The division the second length's fraction is counted in.
It need not match the first length's: a quarter can be added to seven sixteenths, and the answer is worked exactly before it is rounded to a mark.
The finest mark you will actually find on the rule you are marking with.
Rounding finer than your tape is marked only produces a mark you cannot locate, and it then gets rounded again by eye. The decimal figures are not rounded to a mark, whichever you choose.
Answer in inches, with the tape reading
132.25 in (11 ft 0 1/4 in)
Worked to full precision: each length becomes inches, twelve to the foot, the sum, difference, product or quotient is worked from them, and the answer comes back as feet and inches. Inches and millimetres are printed in full, to six decimal places at most, where any sum of sixty-fourths ends; decimal feet, and a quotient that never ends, are cut at the sixth place. Only the tape reading is rounded to a mark: the nearest at the fraction chosen, and a value exactly halfway between two marks goes to the one further from zero. The last row says how far the reading moved and which way: positive when the mark is longer than the answer, and on a negative answer, negative when the shortfall reads larger.
- Decimal feet
- 11.020833 ft
- Millimetres
- 3,359.15 mm
- Tape mark minus the exact answer, in millimetres
- 0 mm
- First length, in inches
- 99.5 in (8 ft 3 1/2 in)
- Second length, in inches
- 32.75 in (2 ft 8 3/4 in)
They open the calculator with your figures already in it
Feet and Inches Calculator (Add, Subtract, Multiply, Divide): 132 in (11 ft 0 1/4 in) — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- NIST Handbook 44 (2026 edition), Appendix C, General Tables of Units of Measurement: 12 inches = 1 foot; 1 inch = 2.54 centimetres exactly and 1 foot = 0.3048 metre exactly, per the Federal Register of 1 July 1959 (24 FR 5348); and, on converting, that rounding should be the last step and performed only once
- NIST Handbook 44 (2026 edition), Section 5.52 Linear Measures: S.1, a linear measure may be subdivided in inches and binary submultiples of the inch; Table 2, maintenance and acceptance tolerances for metal tapes of 1/32 in up to 6 ft and 1/16 in from 7 to 30 ft
Inputs used
- First Length: Feet (ft)
- 8
- First Length: Inches (in)
- 3
- First Length: Fraction, Top Number
- 1
- First Length: Fraction, Bottom Number
- 2 (halves)
- Second Value Is
- A length: add or subtract
- Add or Subtract
- Add: first + second
- Second Length: Feet (ft)
- 2
- Second Length: Inches (in)
- 8
- Second Length: Fraction, Top Number
- 3
- Second Length: Fraction, Bottom Number
- 4 (quarters)
- Multiply or Divide
- Multiply: first × the number
- The Number
- 3
- Round the Tape Reading to the Nearest
- 1/16 in, an everyday tape
Intermediate steps
- Decimal feet
- 11.020833 ft
- Millimetres
- 3,359.15 mm
- Tape mark minus the exact answer, in millimetres
- 0 mm
- First length, in inches
- 99.5 in (8 ft 3 1/2 in)
- Second length, in inches
- 32.75 in (2 ft 8 3/4 in)
Confidence note: Worked to full precision: each length becomes inches, twelve to the foot, the sum, difference, product or quotient is worked from them, and the answer comes back as feet and inches. Inches and millimetres are printed in full, to six decimal places at most, where any sum of sixty-fourths ends; decimal feet, and a quotient that never ends, are cut at the sixth place. Only the tape reading is rounded to a mark: the nearest at the fraction chosen, and a value exactly halfway between two marks goes to the one further from zero. The last row says how far the reading moved and which way: positive when the mark is longer than the answer, and on a negative answer, negative when the shortfall reads larger.
What this calculation does not cover
- The tape reading is the nearest mark in either direction, so it can sit up to half a mark long or short of the exact answer: 1/128 in (0.2 mm) when reading to sixty-fourths, 1/64 in (0.4 mm) to thirty-seconds, 1/32 in (0.8 mm) to sixteenths and 1/16 in (1.6 mm) to eighths. A part that must not come out short, or a gap that must not close up, is marked toward the side its tolerance allows rather than to the nearest mark.
- Dividing shares out a length, not a board. Every saw cut turns the width of the blade into dust, so a board cut into three equal pieces takes two cuts and each piece comes out shorter than a third of the board. Take one blade width off the length for every cut before dividing, or mark each piece from the same end and cut on the waste side of the line.
- Multiplying gives the total of so many equal lengths and nothing more: offcuts, squared-off ends and spoiled pieces are not in it, and nor is the fact that a stock length only yields whole pieces. Ordering stock from the total alone comes up short.
- The page works on the figures as typed and cannot know which faces they were taken to. Taking an opening's width off a wall's length gives the space either side only when both were measured to the same surfaces, finish to finish or framing to framing, with the casing and the plaster treated the same way in both.
- A decimal in a box is read as a decimal of that box's unit: 8.5 in the feet box is 8 ft 6 in, not 8 ft 5 in, and 3.5 in the inches box is three and a half inches. The fraction beside a length is added on top of whatever its inches box holds, and a top number larger than the bottom one carries whole inches with it.
Add the equipment this sizes
This result is a specification — 132.25 in (11 ft 0 1/4 in) — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-10-05 · v1.0.0
Regulatory standards & verification citations2
- NIST Handbook 44 (2026 edition), Appendix C, General Tables of Units of Measurement: 12 inches = 1 foot; 1 inch = 2.54 centimetres exactly and 1 foot = 0.3048 metre exactly, per the Federal Register of 1 July 1959 (24 FR 5348); and, on converting, that rounding should be the last step and performed only once
- NIST Handbook 44 (2026 edition), Section 5.52 Linear Measures: S.1, a linear measure may be subdivided in inches and binary submultiples of the inch; Table 2, maintenance and acceptance tolerances for metal tapes of 1/32 in up to 6 ft and 1/16 in from 7 to 30 ft
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