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Add, subtract, multiply, and divide fractions with exact rational arithmetic — no floating-point drift. Simplifies automatically.
Fraction Calculator is loading — interactive editor will appear here. Use examples below to try instantly once loaded.
Press ? for keyboard shortcuts
Adds, subtracts, multiplies, and divides two fractions (or mixed numbers, integers, or decimals) and returns the exact result reduced to lowest terms — plus the mixed-number and decimal forms.
Calculators that convert everything to decimals produce rounding errors (0.1 + 0.2 ≠ 0.3 in binary floating point). This calculator keeps every intermediate value as an exact integer numerator/denominator pair and reduces by the greatest common divisor, so 1/3 + 1/6 really is 1/2, exactly.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
Students checking homework, teachers preparing answer keys, cooks halving or doubling recipes, woodworkers and machinists working in sixteenths and eighths, and anyone who needs an exact answer rather than a decimal approximation.
Enter the first value — a fraction (3/4), mixed number (1 1/2), integer (7), or decimal (2.5)
Pick the operation (+, −, ×, ÷) from the dropdown
Enter the second value
Read the results panel: simplified fraction, mixed number, and decimal
Divide by zero produces a clear error instead of a wrong answer
1/2 + 1/3 = 5/63/4 − 1/2 = 1/42/3 × 3/4 = 1/21/2 ÷ 1/4 = 21 1/2 + 2/3 = 2 1/62.5 × 4/5 = 2Q: Does it handle negative fractions? A: Yes
the sign follows standard rules and is normalized onto the numerator.
Q: Are decimals exact or approximate?
A: Decimals you enter are converted to exact fractions first (2.5 → 5/2), so no binary floating-point error enters the calculation.
Q: What is the largest input I can use?
A: Numerators and denominators up to about 10^15 (JavaScript's safe-integer range); products are reduced at each step to avoid overflow in everyday use.
Q: Can I chain operations like 1/2 + 1/3 + 1/4? A: Do them pairwise, or use the Scientific Calculator for longer expressions
it evaluates the whole expression at once.
Authoritative specifications, standards, and in-depth reading for Fraction Calculator.
Result (simplified)
1/2 + 1/3 = 5/6
Mixed number: 5/6 · Decimal: 0.8333333333
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