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Fractions Calculator

Add, subtract, multiply and divide fractions. Perfect for measurements and cuts.

Fractions
Enter fractions in any format: 1/2, 1 1/2, 0.5, etc.
Result
Enter fractions and click Calculate to see results

About the Fractions Calculator

This fraction calculator adds, subtracts, multiplies, and divides fractions and mixed numbers, then reduces the answer to its simplest form. It is built for the workshop and the classroom alike, where measurements arrive as halves, quarters, eighths, and sixteenths rather than tidy decimals.

Working with fractions

A fraction represents a part of a whole: the bottom number (denominator) says how many equal pieces the whole is divided into, and the top number (numerator) says how many of those pieces you have. To add or subtract fractions they must share the same denominator, so the calculator first finds a common denominator, combines the numerators, and then simplifies. Multiplication and division are more direct — multiply across, or invert and multiply to divide.

Mixed numbers such as 1 1/2 are converted to improper fractions (3/2) before the arithmetic, then converted back at the end so the result reads naturally. The final answer is always reduced by dividing the numerator and denominator by their greatest common divisor.

Why fractions matter in the shop

Tape measures, drill bits, router bits, and hardware are dimensioned in fractions of an inch, so a maker constantly adds and subtracts them — figuring a shoulder offset, splitting a board into equal strips, or working out how much to trim. Doing this in your head is error-prone, especially with sixteenths and thirty-seconds, and a single mistake can ruin a workpiece.

Keeping answers in fractional form (rather than converting to decimals) means your result matches the markings on your tape, so there is no rounding step between the calculation and the cut.

Worked example

You need to add a 3/4 inch shoulder to a 5/8 inch tenon to find the total length.

  1. Common denominator of 4 and 8 is 8.
  2. Convert: 3/4 = 6/8, leave 5/8 as is.
  3. Add numerators: 6/8 + 5/8 = 11/8.
  4. Convert to a mixed number: 11/8 = 1 3/8.

The total length is 1 3/8 inches.

Frequently asked questions

How do I add fractions with different denominators?

Find a common denominator (a number both denominators divide into evenly), rewrite each fraction with that denominator, add the numerators, and simplify. The calculator does all of these steps automatically.

Can I enter mixed numbers like 2 3/8?

Yes. Enter the whole number and the fraction together (for example '2 3/8'). The calculator converts to an improper fraction internally and returns the answer as a simplified mixed number.

Does it simplify the answer automatically?

Yes. Every result is reduced to lowest terms by dividing the numerator and denominator by their greatest common divisor, so 8/16 is shown as 1/2.

Can I convert a fraction to a decimal?

Dividing the numerator by the denominator gives the decimal equivalent — for example 3/8 = 0.375. For unit and fraction-to-decimal conversions across measurement types, use the unit converter.