Fraction calculator
Add, subtract, multiply, divide and simplify fractions with the full common-denominator and reduction steps, plus mixed numbers, decimals, decimal ↔ fraction conversion and GCD/LCM.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
5/65/60.8333331/2 + 1/3 = (1 × 3) / 6 + (1 × 2) / 6 = 3/6 + 2/6 = 5/6
What this tool does
- Check fraction homework or your own working: 3/4 + 1/6 shows the common-denominator steps (lcm(4, 6) = 12 → 9/12 + 2/12) and reduces to 11/12.
- Get every notation for one answer at once: simplified fraction, mixed number (-7/3 → -2 1/3) and decimal.
- Convert decimals exactly: 0.75 becomes 3/4 with gcd(75, 100) = 25 shown, while float noise like 0.3333333333333333 is turned into 1/3 via continued fractions.
- Handle GCD / LCM or simplify a fraction without doing long division by hand.
Example
Input
3/4 + 1/6
Output
3/4 + 1/6 = (3 × 3) / 12 + (1 × 2) / 12 = 9/12 + 2/12 = 11/12 Simplified 11/12; mixed number 11/12; decimal 0.916667
Numerators and denominators are BigInt throughout, so addition, common denominators and reduction never touch floating point and you never see 0.5000000000000001. Only the decimal display is rounded.
Frequently asked questions
Can fraction arithmetic drift due to floating point?
No. Numerator and denominator are exact BigInt values, and every operation — add, subtract, multiply, divide, common denominator, reduction — is integer arithmetic, so 1/3 + 1/6 is exactly 1/2. Only the decimal display converts to a float and rounds to the digits you choose.
Which input formats are accepted?
3/4, -3/4, plain integers like 5, and mixed numbers like 2 1/2. A zero denominator is rejected outright, and the sign of a mixed number belongs to the whole part (-2 1/3 means -(2 + 1/3)).
Why does 0.3333333333333333 become 1/3?
The exact denominator 10000000000000000 exceeds the denominator limit (1000000), so the tool falls back to a continued-fraction approximation and returns 1/3. The steps mark that case with ≈ instead of =; short finite decimals such as 0.75 always give an exact fraction.
What is the difference between the simplified fraction and the mixed number?
The simplified fraction is the improper form with coprime numerator and denominator, such as 7/3. The mixed number splits it into an integer and a proper fraction, written 2 1/3. For negatives the sign sits on the integer part, and values below 1 stay proper fractions.
Is my input uploaded?
No. All arithmetic runs in your browser with BigInt, the page sends no network requests, and the numbers you enter are never recorded.
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