Pythagorist
Fractions

Subtracting Fractions Calculator

Subtract any two fractions with full step-by-step working shown. Handles different denominators, mixed numbers and negative results.

First fraction
-Subtract
Second fraction
14\frac{1}{4}

= 0.25 (decimal)

Step-by-step working

  1. Find the lowest common denominator (LCD)

    LCD(2, 4)=4\text{LCD}(2,\, 4) = 4

    The lowest common denominator of 2 and 4 is 4.

  2. Convert the first fraction

    12=24\frac{1}{2} = \frac{2}{4}

    Multiply numerator and denominator of the first fraction by 2.

    Result:\frac{2}{4}

  3. Convert the second fraction

    14=14\frac{1}{4} = \frac{1}{4}

    Multiply numerator and denominator of the second fraction by 1.

    Result:\frac{1}{4}

  4. Subtract the numerators

    24−14=14\frac{2}{4} - \frac{1}{4} = \frac{1}{4}

    Subtract the numerators: 2 − 1 = 1. The denominator stays the same.

    Result:\frac{1}{4}

The formula

ab−cd=ad−bcbd\frac{a}{b} - \frac{c}{d} = \frac{ad - bc}{bd}
a,ca, cNumerators
b,db, dDenominators

Example substitution

34−13=912−412=512\frac{3}{4} - \frac{1}{3} = \frac{9}{12} - \frac{4}{12} = \frac{5}{12}

LCD of 4 and 3 is 12. Convert and subtract.

Worked examples

3/4 − 1/4

  1. 1
    Same denominator: 4
  2. 2
    Subtract: 3 − 1 = 2
  3. 3
    Result: 2/4 = 1/2
Answer: 1/2

5/6 − 1/4

  1. 1
    LCD(6,4): = 12
  2. 2
    Convert: 10/12 − 3/12
  3. 3
    Subtract: 7/12
Answer: 7/12

1 − 1/3

  1. 1
    Write as fraction: 3/3
  2. 2
    Subtract: 3/3 − 1/3
  3. 3
    Result: 2/3
Answer: 2/3

Frequently asked questions

How do you subtract fractions?+

Find a common denominator, convert both fractions, subtract the second numerator from the first, then simplify the result.

What if the answer is negative?+

If the second fraction is larger than the first, the result is a negative fraction. This is perfectly valid — the calculator handles it automatically.

How do you subtract a fraction from a whole number?+

Write the whole number as a fraction with denominator 1, find the common denominator, then subtract.

How do you subtract mixed numbers?+

Convert each mixed number to an improper fraction, subtract, then convert the result back to a mixed number and simplify.

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