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Tape measure calculator

Feet and inches calculator with fractions

Add, subtract, multiply and divide lengths exactly as they read on the tape: 12' 6 1/2" plus 8' 9 3/4" is 21' 4 1/4". No decimals to convert, no carrying by hand.

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  • Fractions from 1/2" to 1/64"
  • Metric conversion
  • A tape of every result
FT-IN1/16

12' 6½" + 8' 9¾"

21' 4¼"

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How to use it

Type the measurement the way you say it

The keypad has Feet and Inch keys and a fraction key, like a handheld construction calculator.

  1. Enter the first length

    12, Feet, 6, Inch, 1, fraction, 2 gives 12' 6 1/2".

  2. Pick the operation

    +, −, × or ÷. Multiply or divide by a plain number to scale or split a length.

  3. Read the answer

    In feet, inches and the fraction you choose, or converted to decimal feet, inches or metric.

Examples

Everyday tape-measure math

  • 12' 6½" + 8' 9¾"

    21' 4¼"

    Add two lengths

  • 12' 0" − 2' 7⅝"

    9' 4⅜"

    Take off a cut

  • 10' 3" ÷ 4

    2' 6¾"

    Four equal bays

  • 12' × 10'

    120sq ft

    Two lengths make an area

Beyond adding

Guided tools for the job in front of you

  • Concrete calculator

    Cubic yards to order for a slab or footing, with waste and weight, from feet and inches.

  • Stair calculator

    Equal risers and treads, the stringer length and the stairwell opening from one total rise.

  • Roof pitch calculator

    Pitch as x/12, degrees and percent, with the common rafter length for your run.

  • Square footage calculator

    Area, perimeter and the square-up diagonal of any room, slab or panel, in feet and inches.

Questions

How do I add feet and inches by hand?

Add the feet, add the inches, then carry: every 12 inches is 1 foot. 5' 9" + 3' 8" is 8' 17", which is 9' 5". The calculator does the carrying, and the fractions, for you.

How do I enter a fraction like 6 1/2 inches?

Press 6, then Inch, then 1, the fraction key and 2. Feet go in the same way with the Feet key, so 12 Feet 6 Inch 1 / 2 is 12' 6 1/2".

Can I multiply feet by feet?

Yes. Two lengths give square feet and three give cubic feet or cubic yards, which is how a slab becomes yards of concrete.

Does it convert to millimetres and metres?

Yes. The Convert key changes a result between feet and inches, inches, yards, millimetres, centimetres and metres.

How exact is the answer?

The math runs at full precision and rounds once, for display, to the fraction you choose: 1/2, 1/4, 1/8, 1/16, 1/32 or 1/64 inch.