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Subtract fractions

Enter two fractions and see the difference simplified, as a mixed number and as a decimal. The steps show the common denominator and how the numerators are subtracted.

For example 3/4, 1 1/2, −2 or 0.25.

Fill in the fields; the answer appears here straight away.

How it works

  1. Enter the values

    Type the numbers or the formula. Decimals may use a point or a comma. No idea? Click Fill in an example.

  2. Instant answer

    The answer appears as you type, with the most important intermediate values.

  3. See the working

    Under "How it's worked out" you see the steps, handy for checking your own calculation.

How to subtract fractions

  1. Make the denominators equal. For 5/6 − 1/4 the least common multiple of 6 and 4 is 12: 5/6 = 10/12 and 1/4 = 3/12.
  2. Subtract the numerators. 10/12 − 3/12 = 7/12.
  3. Simplify where possible.

If the second fraction is larger, the answer is negative: 1/4 − 5/6 = −7/12.

Input

Fractions (3/4), mixed numbers (2 1/3), whole numbers and decimals all work, as do negative numbers. Everything is calculated exactly. To add instead, use add fractions.

Worked example with mixed numbers

Subtract 1 3/4 from 3 1/2. As improper fractions that is 7/2 − 7/4. The common denominator is 4, so 7/2 becomes 14/4, and 14/4 − 7/4 = 7/4. Written as a mixed number, the difference is 1 3/4, or 1.75 as a decimal.

A whole number minus a fraction

Take 2 − 3/5. Two wholes is 10/5, so 10/5 − 3/5 = 7/5 = 1 2/5. Enter 2 in the first box and 3/5 in the second to see the same steps.

A common mistake

3/4 − 1/2 is not 2/2. Subtracting numerators and denominators separately breaks the meaning of the fraction. First write 1/2 as 2/4, then 3/4 − 2/4 = 1/4. For adding, see add fractions; for the common denominator, the LCM calculator.

Frequently asked questions

Can the answer be negative?

Yes. If the second fraction is larger, the result is below zero: 1/4 − 5/6 = −7/12. The calculator shows the sign and simplifies as usual.

How do I subtract a fraction from a whole number?

Write the whole number as a fraction with the same denominator. 2 − 3/5 is 10/5 − 3/5 = 7/5, or 1 2/5. In the calculator just enter 2 as the first number.

Why must the denominators match?

The denominator says how big each piece is. You can only subtract pieces of the same size, so both fractions are rewritten with their least common denominator first.

How do I subtract mixed numbers?

Convert both to improper fractions, subtract, and simplify. 3 1/2 − 1 3/4 is 14/4 − 7/4 = 7/4, which is 1 3/4.