Fraction Calculator

FRACTIONS & RATIOS

Add, subtract, multiply, or divide two fractions, with the answer simplified and shown as a decimal. Enter the fractions and an operation.

Result
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Simplified fraction.

Usage Tip

To add fractions fast, the common denominator is at most the product of the two denominators; simplifying at the end keeps the numbers small.

THE MATH
Add or subtract: put over a common denominator
Multiply: numerators and denominators straight across
Divide: multiply by the reciprocal of the second
Fractions combine by matching denominators for addition and subtraction, multiplying across for products, and flipping the divisor for division.
The result is reduced to lowest terms.
Enter whole numbers for each numerator and denominator.
The answer is simplified and also shown as a decimal and a mixed number.
A denominator of zero is undefined.
Practical Notes

To add or subtract fractions, convert them to a common denominator first, then combine the numerators. To multiply, multiply the numerators together and the denominators together. To divide, flip the second fraction and multiply. The result is simplified by dividing the top and bottom by their greatest common factor.

For example, one half plus one third is three sixths plus two sixths, which equals five sixths. The decimal value is shown next to the fraction so you can see the size at a glance. Dividing by a fraction with a zero numerator, or using a zero denominator, is undefined. Fractions are exact, which makes them useful in woodworking, cooking, and any measurement where rounding would add up.

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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.