How to use the woodworking fraction calculator
- Enter a decimal, a fraction such as 3/8, or a mixed number such as 12 3/8.
- Choose the arithmetic operation. A space separates the whole number from the fractional part.
- Choose the tape-measure increment. The displayed fraction is rounded to that increment.
The formula
Convert mixed numbers to decimal values, perform the selected operation, then round to the selected denominator.
Worked example
12 3/8 + 3 1/4 = 15 5/8 inches, or 15.625 inches in decimal form.
Before you measure and cut
Do not include inch marks, feet symbols, or a hyphen in a mixed number. Enter 2 1/2 rather than 2-1/2.
Adding and subtracting lengths preserves length units. Multiplying two lengths produces area, while dividing two lengths gives a ratio.
Frequently asked questions
Does the fraction always exactly equal the decimal?
No. It is rounded to the selected denominator. The decimal result is shown separately so you can see the difference.
Can I enter negative values?
Yes. For example, -1 1/2 means negative one and one-half.