Feet and Inches Calculator

By Calxy · Calculation methodology

Add, subtract, multiply or divide tape-measure lengths in feet, inches and fractions of an inch, and get the answer rounded to the nearest 1/16 inch plus decimal feet and metric.

Printed from Calxy · https://www.calxy.net/other/feet-and-inches-calculator

Result8′ 4 1/8″
ft

0 – 10000000

in

0 – 100000000

ft

0 – 10000000

in

0 – 100000000

Result

8′ 4 1/8″

  • Total inches100.1250 in
  • Decimal feet8.3438 ft
  • Meters2.5432 m
  • Centimeters254.32 cm
  • Rounding difference0.0000 in

1 ft = 12 in and 1 in = 2.54 cm exactly (international inch). The fraction is rounded to your chosen tape-measure precision; decimal and metric values are unrounded.

How this was calculated

A = 5′ 7 + 6/16″ = 67.375 in.

B = 2′ 8 + 12/16″ = 32.75 in.

A + B = 67.375 + 32.75 = 100.125 in.

100.125 in = 8 ft and 4.125 in; rounded to the nearest 1/16″ that is 8′ 4 1/8″.

How the arithmetic works

Each length is converted to inches: total inches = feet × 12 + inches + fraction. The operation is done in inches, then the result is converted back: feet = whole number of (inches ÷ 12), and the remainder is split into whole inches and a fraction rounded to your chosen precision and reduced (8/16 becomes 1/2).

Metric values use the exact international definition 1 inch = 2.54 cm, so 1 foot = 0.3048 m.

Worked example

5′ 7 3/8″ + 2′ 8 3/4″: A = 5 × 12 + 7 + 0.375 = 67.375 in and B = 2 × 12 + 8 + 0.75 = 32.75 in. The sum is 100.125 in, which is 8 ft (96 in) plus 4.125 in, or 8′ 4 1/8″. That is 8.3438 decimal feet and 2.5432 m.

To cut 30-inch pieces from an 8-foot board, choose How many B fit in A: 96 ÷ 30 = 3.2, so you get 3 whole pieces with 6 inches left over, before allowing for saw kerf.

Rounding

The feet-inches result is rounded to the nearest 1/2, 1/4, 1/8 or 1/16 inch, and the rounding difference is shown. Total inches, decimal feet and metric values are not rounded. Negative results from subtraction are shown with a minus sign.

How to use the Feet and Inches Calculator

Choose an operation and enter the lengths.

  1. Choose the operation

    Pick add, subtract, multiply or divide by a number, or how many B fit in A.

  2. Enter the lengths

    Type feet and inches and pick a fraction of an inch for each length.

  3. Choose the precision

    Round the result to the nearest 1/2, 1/4, 1/8 or 1/16 inch.

  4. Read the result

    See feet-inches-fraction, total inches, decimal feet and metric.

References

Frequently asked questions

How do I enter 3/8 of an inch?

Choose 3/8 from the fraction list. The list runs in sixteenths and shows reduced fractions, so 6/16 is displayed as 3/8.

How do I convert feet and inches to decimal feet?

Divide the inches by 12 and add the feet. 8′ 4 1/8″ is 8 + 4.125 ÷ 12 = 8.3438 ft. The calculator shows this for every result.

Can I multiply two lengths to get area?

No. Multiply and divide here scale a length by a number. For areas, use the square footage calculator.

Last updated . Results are estimates for informational purposes only.