# Fraction Calculator - Add, Subtract, Multiply, Divide and Simplify

> Free online fraction calculator: add, subtract, multiply and divide fractions with automatic reduction, plus fraction ↔ decimal with repeating digits.

- URL: https://qilingtools.com/en/math/fraction
- Category: Math Tools (https://qilingtools.com/en/math)
- Tags: [Math](https://qilingtools.com/en/tags/math), [Education](https://qilingtools.com/en/tags/education)
- Last updated: 2026-10-26
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

Do fraction arithmetic without the paperwork: enter two fractions and an operator for an automatically reduced answer, simplify a fraction to lowest terms, turn a fraction into a decimal with the repeating part marked, or turn a decimal — including a repeating one — back into a fraction.

## How to use

1. Choose fraction math, simplify, fraction → decimal or decimal → fraction
2. Type the numerator and denominator (and pick + − × ÷ for arithmetic)
3. Read the answer in lowest terms, as a mixed number, a decimal and a percentage

## Features

- Automatic common denominators and reduction
- BigInt arithmetic, so large numerators stay exact
- Repeating decimals detected, e.g. 1/7 = 0.(142857)
- Write 0.1(6) to convert a repeating decimal back to a fraction
- Mixed number, decimal and percentage shown together

## FAQ

### How do I type a repeating decimal?

Put the repeating digits in brackets: 0.3(3) is 0.333… and 0.1(6) is 0.1666…, which convert to 1/3 and 1/6.

### Why is the answer always in lowest terms?

The result is divided by the greatest common divisor of numerator and denominator, and the sign is moved to the numerator.

### Are big numbers supported?

Yes. Arithmetic uses BigInt internally, so even numerators with dozens of digits stay exact.

### Can the denominator be 0?

No — a fraction with denominator 0 is undefined, and the tool will tell you so.

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