Fraction Calculator
Last updated: November 4, 2026
Add, subtract, multiply or divide two signed fractions and retain an exact reduced fraction.
On this page
Quick summary: Add, subtract, multiply or divide two signed fractions and retain an exact reduced fraction.
Read the complete guide
Updated reference sections in this guide are in English.
Using this calculator
Enter each fraction as a separate numerator and denominator. Use signed whole numbers without decimal dots or scientific notation. A negative denominator is accepted and normalized to a positive denominator. Choose the operation before calculating; subtraction and division use the first fraction followed by the second.
Calculation method
a/b − c/d = (ad − bc) / bd
(a/b)(c/d) = ac / bd
(a/b) ÷ (c/d) = ad / bc
After the operation, the numerator and denominator are divided by their greatest common factor. Browser BigInt arithmetic keeps these integer steps exact. The mixed-number view and an approximate decimal are shown separately so that a repeating decimal is not mistaken for an exact value.
Worked examples
Addition with different denominators
1/2 + 1/3 = (3 + 2)/6 = 5/6. Its decimal is approximately 0.833333333333.
A signed mixed number
−7/3 × 1/1 remains −7/3. The mixed form is −2 1/3, meaning −(2 + 1/3).
Check this scenario in the calculator:
- Operation
- Add
- First numerator
- 1
- First denominator
- 2
- Second numerator
- 1
- Second denominator
- 3
Understanding the result
A whole-number result is displayed without “/ 1”. A zero numerator reduces to 0/1 internally. Reducing a fraction changes its representation, not its value. Mixed numbers are an alternative reading of the same signed result; type them into this form as improper fractions.
Boundaries and assumptions
Each input permits at most 18 digits plus a sign. Neither denominator may be zero, and the fraction used as a divisor must be nonzero. Fraction results are exact within those input limits. Decimal results use floating-point conversion and may round; they should not replace the exact fraction in further symbolic work.
Questions and reference
How do I enter 2 1/3?
Convert it to 7/3 first: multiply the whole part by the denominator and add the numerator.
Can I enter Arabic digits?
Yes. Arabic and Persian integer digits are normalized before exact integer calculation.