Free Fraction Calculator - Add, Subtract, Multiply & Divide

Calculate with fractions and mixed numbers, simplify any fraction, or convert decimals to fractions. Free and browser-based.

First fraction

Second fraction

Result

5/6

Mixed number

5/6

Decimal

0.833333

Fraction Calculator with Simplification

Add, subtract, multiply, and divide fractions with optional whole-number parts, and get the answer instantly in three forms: a fully simplified improper fraction, a mixed number, and a decimal. The calculator also has a dedicated simplify mode that reduces any fraction to lowest terms, and a decimal-to-fraction mode that finds the closest fraction with a denominator up to 10,000.

Students use it to check homework and understand how fraction arithmetic works, parents use it to help kids without redoing the math by hand, and cooks, woodworkers, and DIYers use it whenever recipes or measurements come in halves, thirds, and sixteenths. Because everything runs in your browser, results appear as you type with no submit button and no waiting.

Behind the scenes the calculator uses cross multiplication for addition and subtraction, straight numerator and denominator products for multiplication, and reciprocal multiplication for division. Every result is reduced using the greatest common divisor, computed with the Euclidean algorithm, which is the same method taught in school for finding lowest terms. Mixed inputs such as 2 1/3 are converted to improper fractions before calculating.

The decimal-to-fraction mode uses a Stern-Brocot search to find the best rational approximation. For example, 0.625 becomes exactly 5/8, and 0.333333 becomes 1/3 rather than 333333/1000000. With a denominator cap of 10,000 the approximation is accurate to at least four decimal places for any input, which covers practical use cases from measurements to probability.

Working with percentages instead? Our Percentage Calculator handles discounts, increases, and ratios with the same instant feedback, and converting a fraction to a percentage is as simple as reading the decimal output here and multiplying by 100. If you need averages and weighted scores for school, the GPA Calculator and Grade Calculator on ToolForte apply the same careful arithmetic to grading, and the Roman Numeral Converter covers a very different kind of number notation. Everything runs free in your browser.

How the Fraction Calculator Works

  1. 01Choose a mode: calculate with two fractions, simplify one fraction, or convert a decimal.
  2. 02Enter each fraction with an optional whole-number part, numerator, and denominator.
  3. 03Pick the operation: add, subtract, multiply, or divide.
  4. 04Read the result as a simplified fraction, a mixed number, and a decimal, updated as you type.

Working Confidently with Fractions

Fraction arithmetic follows four rules and this calculator applies them all while showing its work through the result formats. Addition and subtraction need a common denominator: a/b + c/d = (ad + cb)/bd, which is then reduced. Multiplication is straight across: numerators together, denominators together. Division flips the second fraction and multiplies. Mixed numbers like 2 1/3 are converted internally to improper fractions (7/3) before any operation, so you can enter measurements the way they appear on tape measures and recipes. Every result is reduced with the greatest common divisor, so 8/12 always comes back as 2/3. The simplify mode is useful on its own for reducing answers from homework or recipe scaling, and the decimal mode finds the nearest fraction with a denominator up to 10,000, which turns 0.375 into exactly 3/8 and 1.667 into 5/3. If you see an error, check for a zero denominator, the one thing fraction math can never allow.

When to Use the Fraction Calculator

Reach for it whenever quantities come in parts rather than decimals: scaling a recipe from 4 to 6 servings, adding lumber measurements in inches, checking a child's math homework, splitting things fairly, or converting a decimal from a calculator back into the fraction a woodworking plan expects. It is faster and less error-prone than finding common denominators by hand, and the three output formats mean you always get the form you need.

Common Use Cases

  • Scale recipe quantities: three quarters of a cup times one and a half.
  • Add tape-measure fractions when cutting wood or fabric.
  • Check fraction homework with the full simplified, mixed, and decimal answers.
  • Convert calculator decimals back to exact fractions for a plan or pattern.
  • Verify percentage-to-fraction conversions before a test. → Percentage Calculator

Expert Tips

  • Dividing by a fraction multiplies by its reciprocal: dividing by 1/2 doubles the result, which surprises many students the first time.
  • For recipe scaling, multiply the fraction by the serving ratio as a fraction (6/4 = 3/2) instead of converting to messy decimals.
  • The decimal mode reveals repeating decimals: 0.333333 comes back as 1/3, which tells you the original number was a fraction all along.

Frequently Asked Questions

Can I enter mixed numbers like 2 1/2?→
Yes. Each fraction has an optional whole-number field. 2 1/2 is treated as 5/2 internally, and results are shown as mixed numbers too.
How are negative fractions handled?→
Put the minus sign on the whole number, or on the numerator when there is no whole part. The sign carries through the calculation correctly.
How accurate is decimal to fraction conversion?→
The converter searches for the best fraction with a denominator up to 10,000, which is accurate to at least four decimal places. Exact decimals like 0.625 convert perfectly to 5/8.
Why is my result already simplified?→
Every result is automatically reduced to lowest terms using the greatest common divisor, the standard convention in math courses.

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