Softonic

Fraction Calculator

Step 1 / 4 Fraction math
Next: operator

Doing fraction arithmetic in your head is error-prone once denominators stop sharing factors. Give this calculator two fractions — ordinary or mixed — pick an operation, and it returns the result in lowest terms with the common-denominator step shown so you can check the work.

How to compute a fraction

  1. 1

    Enter the first fraction

    Type numerator and denominator, or a mixed number like 2 1/3.

  2. 2

    Pick an operator

    Choose +, −, × or ÷.

  3. 3

    Enter the second fraction

    Same format — whole, fraction or mixed.

  4. 4

    Read the result

    Output appears as a fraction in lowest terms plus the decimal equivalent.

Rules behind each operation

Operation Rule
Add a/b + c/d = (ad + bc) / bd, then simplify by GCD
Subtract a/b − c/d = (ad − bc) / bd
Multiply a/b × c/d = ac / bd
Divide a/b ÷ c/d = a/b × d/c = ad / bc

The calculator simplifies every answer by dividing numerator and denominator by their greatest common divisor (Euclidean algorithm), so 6/8 becomes 3/4.

Mixed numbers

A mixed number like 2 3/4 is converted to an improper fraction first: 2 3/4 = (2×4 + 3)/4 = 11/4. If the final answer is improper (numerator ≥ denominator), it is shown both as improper and as a mixed number.

Common pitfalls

  • Forgetting to simplify. 8/12 and 2/3 are equal; teachers almost always want the reduced form.
  • Negative signs on the denominator. −3/4 and 3/−4 and −(3/4) are the same number; this tool canonicalises to the numerator.
  • Dividing by zero. a/b ÷ 0/d is undefined — the tool flags it rather than returning infinity.
  • Mixed-number spacing. “2 1/3” with a space is a mixed number; “21/3” is seven.

Frequently Asked Questions

Yes. Put the minus sign before the whole or the numerator: −2 1/3 or −7/3. Subtraction of negatives follows standard algebra, so 1/2 − (−1/4) equals 3/4.

US schoolwork typically expects mixed numbers (“1 1/2”), while engineering, cooking and algebra keep things improper (“3/2”). Both are valid; different conventions want different forms.

It computes the greatest common divisor of numerator and denominator with the Euclidean algorithm and divides both by it. The result is always in lowest terms.

No. The numbers you type are evaluated locally and discarded as soon as you leave the page.

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