Add, subtract, multiply, divide, and simplify fractions
Fractions are easier when the arithmetic is handled for you. This calculator adds, subtracts, multiplies, and divides two fractions, always reducing the result to its simplest form. It also shows the decimal value and, for improper results, the equivalent mixed number.
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Advanced calculator with scientific functions and history
Calculate aspect ratios, resize dimensions while maintaining proportions. Common presets for video, photo, mobile screens, and social media
Calculate exact age in years, months, and days. Find date differences, countdowns, zodiac signs, and detailed time breakdowns
A recipe scaling needs 1/2 + 1/3 of a cup expressed as a single exact fraction, not a rounded decimal.
Expression
1/2 + 1/3
Result
5/6 (≈ 0.8333), already in lowest terms
The fractions are placed over the least common denominator (6), added, then reduced by the greatest common divisor, giving an exact answer where a decimal would silently round. It also converts between improper fractions and mixed numbers.
Fractions are easier when the arithmetic is handled for you. This calculator adds, subtracts, multiplies, and divides two fractions, always reducing the result to its simplest form. It also shows the decimal value and, for improper results, the equivalent mixed number.
Each operation is carried out by cross-multiplication on the raw numerators and denominators rather than by finding a least common denominator first. Addition and subtraction compute (n1*d2 +/- n2*d1) over d1*d2, multiplication uses n1*n2 over d1*d2, and division multiplies by the reciprocal as n1*d2 over d1*n2. The unsimplified product is shown first as the "Original" result, then reduced separately, so you can see both the mechanical answer and its lowest-terms form side by side.
Simplification runs the result through the Euclidean GCD algorithm (the iterative a % b loop) and divides both numerator and denominator by their greatest common divisor; if the denominator comes out negative it flips the sign of both so the denominator stays positive. The simplified fraction is only displayed when it actually differs from the original, the decimal equivalent is shown to six places via toFixed(6), and a mixed-number line appears only for improper results where the absolute numerator exceeds the absolute denominator and the denominator is not 1 (computed with Math.floor and a modulo for the remainder).
Inputs are parsed with parseInt, so values are treated as whole integers and any decimal portion is truncated; an empty numerator defaults to 0 and an empty denominator defaults to 1. A zero denominator, or dividing by a second fraction whose numerator is 0, triggers an alert instead of producing a result. Five quick presets (1/2, 1/3, 1/4, 2/3, 3/4) fill in the second fraction with one click, and the operation plus all four numerator/denominator values are stored in the URL, so a configured calculation can be shared as a link via the Share button.
Solve and verify fraction arithmetic assignments and check the simplified form.
Scale ingredient amounts that are given as fractions, double a recipe calling for 2/3 cup.
Add fractional inch measurements when cutting lumber or laying tile.
Enter fractions as a numerator and denominator (improper fractions such as 11/4 are fine). The result is shown as a mixed number when it is improper, though inputs themselves are entered as numerator/denominator.
The calculator finds the greatest common divisor of the numerator and denominator and divides both by it, keeping the denominator positive.
A zero denominator, or dividing by a fraction with a zero numerator, is undefined, and the tool displays an error.
Every calculation runs locally in your browser. Your numbers and expressions are not transmitted or stored.