Inch fraction calculator
Add or subtract two measurements written the way a tape measure shows them, and read the answer to whatever denominator the tool in your hand actually has marks for.
= 0.375"
= 0.25"
Operation
Read to nearest
That's
5/8"
= 0.625" decimal
About adding up fractions of an inch
- How do you add fractions of an inch?
- Convert both to decimal inches, add or subtract, then convert back to the nearest mark on your tool. 3/8" is 0.375", 1/4" is 0.25", and the two together are 0.625", which is 5/8" on a tape measure. The conversion back is the step people get wrong by hand, because the decimal rarely lands exactly on a sixteenth.
- Why does this let me pick a denominator?
- A tape measure only has marks down to 1/16", but a dial caliper reads 1/64" and a good combination square's fine scale reads 1/32". Reading a caliper measurement to the nearest sixteenth throws away real precision the tool actually gave you, and reading a tape to the nearest sixty-fourth invents precision it never had.
- Why did my answer come out to 0" instead of a fraction?
- It rounded to zero at the denominator you picked — a difference of 1/64" reads as 0" at the nearest sixteenth, because a sixteenth scale has no mark that small. Switch to a finer denominator if the tool you're checking against actually has one.