$Fraction Calculator — a one-half tile with a count badge. Calculates and reduces exact fractions.$

Fraction Calculator

Add, subtract, multiply, divide or simplify fractions and mixed numbers with exact steps.

Work with exact fractions, integers, mixed numbers or finite decimals. See the reduced fraction, mixed form and an explicitly exact or truncated decimal.

Inputs are calculated locally without uploading, adding them to the URL or saving them. Editing a number or operation clears the prior result and download buttons. Files you already downloaded remain on your device.

This tool runs entirely in your browser. Your data is never uploaded, never stored, and never leaves your device.

Calculate exact fraction arithmetic from fractions, mixed numbers, integers or finite decimals, with reduced results and worked steps.

How to use it

1Select a two-number operation or one-number simplify / convert.
2Enter explicit values such as -2 1/3 and 0.125, then calculate.
3Review the exact fraction, mixed form and exact-or-truncated decimal.
4Download TXT or JSON with the active inputs and explanation.

Example

Input: -2 1/3 + 0.125
Output: -53/24 = -2 5/24; decimal -2.208333333333333333333333…

The decimal is truncated toward zero at 24 places; the fraction is exact.

What happens to your data

All arithmetic stays in browser memory without uploads, persistent storage or input URLs. Optional local files contain the entered calculation.

Last updated October 2026

A fraction keeps a ratio exact when a decimal would repeat. This fraction calculator adds, subtracts, multiplies and divides two values, or simplifies one value. You can mix ordinary fractions, integers, mixed numbers and finite decimals in the same calculation. The answer includes a reduced fraction, a mixed form, a decimal and the arithmetic used to obtain it.

The exact answer is calculated with integer arithmetic rather than by first approximating the inputs as binary floating-point numbers. A decimal that needs more than 24 places is labelled truncated, not rounded or exact. TXT and JSON downloads keep the inputs, operation, result and explanation together.

How it works

Enter a fraction such as 3/4, an integer such as 12, a mixed number such as 2 1/3, or a finite decimal such as .125. A slash separates numerator and denominator; spaces around it are allowed. Commas, percentages, exponent notation, Unicode fraction glyphs and expression syntax are deliberately not interpreted. The operation is chosen separately, so an input cannot execute code or hide another calculation.

A mixed number contains a whole-number magnitude and a proper fractional part. For example, -2 1/3 means -(2 + 1/3), which becomes -7/3. It does not mean -2 + 1/3. A mixed fractional numerator must be smaller than its positive denominator. If you already have an improper fraction such as 7/3, enter that directly rather than writing 0 7/3. Signed denominators are accepted for ordinary fractions and normalized to a positive denominator.

Finite decimals are converted exactly using a power-of-ten denominator: 0.125 becomes 125/1000, then 1/8. The greatest common divisor reduces each input. For addition and subtraction, the explanation uses the least common positive denominator, converts both numerators and combines them. For multiplication it multiplies the two numerators and the two denominators. Division multiplies by the reciprocal of the second fraction. A zero-valued divisor is rejected, including 0/7; a zero denominator is never a valid fraction.

The final numerator and denominator are reduced by their greatest common divisor and the sign is moved to the numerator. Zero is normalized to 0/1 internally and displayed as 0. The mixed form separates a whole magnitude from a proper remainder. For negative values, its sign applies to the entire mixed magnitude. A result between -1 and 0 remains a negative proper fraction so there is no misleading negative-zero whole part.

Long division supplies the decimal display. If the remainder becomes zero within 24 places, that decimal is exact. Otherwise, only the first 24 decimal places are retained toward zero and an ellipsis is shown. For example, -1/3 is displayed as -0.333333333333333333333333…; this is not a rounded replacement for the exact fraction. The tool does not claim to identify or mark the repeating cycle.

Each input is capped at 200 characters. Individual integer components have at most 80 digits; a decimal has at most 80 total digits, including entered leading and trailing zeros. These limits bound the integer work and displayed explanations. Simplify / convert uses only the first field, so an inactive second field does not affect its output. All calculations happen in browser memory without saving inputs, uploading them or adding them to the URL. Changing a value or operation clears the prior answer and download controls; downloaded files already on your device are not deleted.

Worked example: A negative mixed number plus a finite decimal

Input: -2 1/3 + 0.125
Result: -7/3 + 1/8 = -53/24 = -2 5/24; decimal -2.208333333333333333333333…

The fraction and mixed form are exact. The displayed decimal is truncated toward zero at 24 decimal places.

Common use cases

Check a recipe-scale addition without replacing a repeating fraction with an approximation.
Convert a finite decimal into its exact reduced fraction.
Review mixed-number signs and reciprocal division step by step.
Keep a downloadable arithmetic record with both the exact fraction and the decimal limitation.

Frequently asked questions

Can I calculate with mixed numbers and decimals together?＋

Yes. Enter each value in its own field and select an operation. For example, -2 1/3 + 0.125 gives -53/24, or -2 5/24. The decimal 0.125 is interpreted exactly as 1/8, not as a rounded measurement.

What does a negative mixed number mean?＋

The sign applies to the whole mixed magnitude: -2 1/3 means -(2 + 1/3) = -7/3. To calculate -2 + 1/3 instead, enter -2 and 1/3 as separate inputs with Add selected.

Why is a decimal marked truncated?＋

A non-terminating or longer decimal cannot be fully displayed within the 24-place limit. Its retained digits are truncated toward zero without rounding. The reduced fraction remains the exact result; use that if exactness matters.

Can I divide by a fraction equal to zero?＋

No. A fraction such as 0/7 equals zero, so its reciprocal is undefined. The tool rejects it as a divisor, just as it rejects a zero denominator in any entered fraction.

Does simplifying change the value?＋

No. Dividing a numerator and denominator by their greatest common divisor preserves their ratio. For example, 42/56 reduces to 3/4. The one-number mode can also convert 0.75 into that same fraction.

Are the downloaded answers exact?＋

The numerator and denominator are exact integer strings in the JSON file, avoiding numeric rounding in programs that preserve strings. The decimal object separately says whether its displayed value terminates exactly or is truncated. TXT contains the same distinction in readable language.