Add, subtract, multiply, or divide fractions — automatically simplified
💡 Why This Matters Fractions show up in cooking, construction, finance, and homework alike, and doing the math by hand — finding common denominators, simplifying results — is easy to get wrong. This tool does the arithmetic and simplification for you, instantly.
Ancient Egyptians almost always used "unit fractions" — fractions with a numerator of 1, like 1/3 or 1/7 — and would break other fractions into sums of them, since their number system had no clean way to write things like 2/5 directly.
As an Amazon Associate we earn from qualifying purchases.
We do our best to link products that we genuinely believe are organic, no disposable junk, sustainable, and built to last.
Each fraction is a numerator (top number) divided by a denominator (bottom number). Adding and subtracting fractions requires a common denominator — the calculator finds one, converts both fractions, then combines the numerators. Multiplying is simpler: multiply the numerators together and the denominators together. Dividing flips the second fraction (its reciprocal) and multiplies. Every result is then simplified to lowest terms by dividing both numerator and denominator by their greatest common factor.
The result is shown as a simplified fraction alongside its decimal equivalent, so you can use whichever form fits your situation — a recipe measurement, a construction cut, or a homework answer. If the result is an "improper" fraction (numerator larger than denominator), it's left in that form rather than converted to a mixed number, since that's the more useful form for further math.
This calculator works with simple numerator/denominator fractions, not mixed numbers directly — convert a mixed number to an improper fraction first (multiply the whole number by the denominator, add the numerator). A denominator of 0 is mathematically undefined and will be flagged rather than silently miscalculated.
Use fraction math for scaling recipes up or down, splitting measurements in woodworking or sewing, working through algebra homework, or dividing shared costs unevenly. Double-check results against a second method (like converting to decimals) when precision really matters, such as in a physical project where a mistake is costly to fix.
Example: Add 1/2 and 1/4. The common denominator is 4, so 1/2 becomes 2/4. Then 2/4 + 1/4 = 3/4. That's already in simplest form — no further reduction needed. Plugging 1/2 and 1/4 into this calculator with Add selected gives you that same 3/4 directly.
Find a common denominator (often the least common multiple of the two denominators), convert both fractions to that denominator, then add the numerators. This calculator does that conversion automatically.
Dividing by a fraction is the same as multiplying by its reciprocal — flipping the numerator and denominator. It's a shortcut that turns division into the multiplication you already know how to do.
Simplifying means dividing the numerator and denominator by their greatest common factor until no common factor remains — turning something like 6/8 into its simplest equivalent, 3/4.
This version works with standard numerator/denominator fractions. Convert a mixed number first by multiplying the whole number by the denominator and adding the numerator — for example, 2 1/3 becomes 7/3.