½ Fraction Subtraction Calculator

Subtract one fraction from another and calculate the exact numerator, denominator and decimal result.

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Enter details

Enter the numerator of the first fraction.
Denominator must not be zero.
Enter the numerator of the second fraction.
Denominator must not be zero.

Fill in the details and click Calculate to see your results.


Also available in our Android app, with charts and full breakdown tables.

📘 About the Fraction Subtraction

Keep the cross-multiplied denominator as a common denominator.

Subtract the cross-multiplied numerators.

A negative result is allowed.

🧮 Formula

Formula
a/b - c/d = (ad - bc)/(bd)
a/b - c/d = (ad - bc)/(bd)

✏️ Worked example

3/4 - 1/6

You enter
First Numerator3
First Denominator4
Second Numerator1
Second Denominator6
You get
Result Numerator14
Result Denominator24
Decimal Result0.583333

The result is 14/24, equivalent to 7/12.

Try this example →

🧭 How to use this calculator

What you enter

  • First NumeratorEnter the numerator of the first fraction.
  • First DenominatorDenominator must not be zero.
  • Second NumeratorEnter the numerator of the second fraction.
  • Second DenominatorDenominator must not be zero.

What you get

  • Result Numerator
  • Result Denominator
  • Decimal Result

💡 Important notes

  • Zero denominators are invalid.
  • The result may be reducible; reduction is not performed by the current engine.

❓ Frequently asked questions

What is the subtraction formula?

Multiply the first numerator by the second denominator, subtract the second numerator times the first denominator, then divide by the product of denominators.

Can the answer be negative?

Yes.

Why is the denominator multiplied?

The product of the denominators is a valid common denominator.