Learn
Fractions from scratch
Fractions are everywhere: on the tape measure, in recipes, in job-site measurements. Once you understand them, everything else gets easier.
What is a fraction?
A fraction is a way to write part of a whole. It has two numbers:
- Numerator (3): how many parts you have.
- Denominator (4): how many parts the whole was split into.
3/4 reads "three quarters": the whole was split into 4 and you took 3.
Simplify (reduce)
Simplifying means writing the fraction with the smallest possible numbers without changing its value. You divide the top and bottom by the same number.
8/16 and 1/2 are worth exactly the same, but 1/2 is easier to read on the tape.
Adding and subtracting fractions
The golden rule: you can only add or subtract fractions with the same denominator (the bottom number). If they're different, make them match first.
Same denominator — easy:
1/8 + 3/8 = 4/8 = 1/2
(add the tops, keep the bottom the same)
Different denominators — match them first:
1/2 + 1/4
1/2 = 2/4 → 2/4 + 1/4 = 3/4
Multiplying and dividing
Multiply: top times top, bottom times bottom.
2/3 × 3/4 = 6/12 = 1/2
Divide: flip the second one and multiply.
1/2 ÷ 1/4 = 1/2 × 4/1 = 4/2 = 2
Turning a fraction into a decimal
Just divide the numerator by the denominator. Handy when your calculator or gauge works in decimals.
Need to add real measurements?
Use the calculator that adds and subtracts inch fractions for you — perfect for the tape measure.
Open the calculator →