Add, subtract, multiply and divide fractions or decimals. Get an exact simplified answer, a rounded decimal and the steps, directly in your browser.
Combine two fractions or decimal values. Use integer numerators and denominators, such as 1/2, or enter a decimal such as 0.5. The answer is given as a fully reduced fraction and as a decimal rounded to six places.
This is for the arithmetic that decimals handle badly: recipe quantities, sixteenths of an inch, thirds of an hour, and homework that must be answered as a fraction in lowest terms. One third stays exactly 1/3 here, never 0.333.
Everything runs in your browser, and the arithmetic uses whole-number (BigInt) maths rather than floating-point, so the printed fraction is exact even when the numbers exceed ordinary decimal precision. Entering 123456789012345678901234567890 over 7 returns 17636684144620811271604938270 with nothing lost.
A denominator of zero is refused with Cannot divide by zero. So is dividing by a second value that equals zero, including a form such as 0/5. Each box takes up to 200 characters, and anything that is not a number or a simple fraction returns a message telling you the accepted formats.
Below the answer, the tool prints the arithmetic it performed. For 2/5 plus 1/4 the steps read: (2 × 4 + 1 × 5) / (5 × 4). Reduce numerator and denominator by their greatest common divisor to get 13/20.
A denominator is not a quantity. It names the size of the pieces you are counting, and the numerator counts how many of those pieces you have. You can only add counts of pieces that are the same size, which is why 2/5 + 1/4 is not 3/9.
Cutting both fractions into pieces of a shared size fixes that. Fifths and quarters both divide evenly into twentieths: 2/5 is 8/20 and 1/4 is 5/20, so the counts add and 8 + 5 gives 13/20. Adding the denominators instead would claim that two fifths plus one quarter is a third, which is smaller than two fifths on its own.
This tool skips the hunt for the lowest common denominator and simply multiplies the two denominators, then reduces; both routes reach the same reduced answer. Our step-by-step guide to adding fractions works through the lowest-common-denominator method by hand if your course asks for it. Multiplication needs no common denominator at all, and division flips the second fraction and multiplies, because dividing by 2/3 is taking three halves of the amount.
Over a common denominator of 20 the parts are 8/20 and 5/20, so the sum is 13/20, shown as Result: 13/20 (decimal: 0.650000). Nothing reduces further, because 13 is prime and does not divide 20.
Multiplying by the reciprocal gives 15/12, which the tool reduces by the greatest common divisor of 3 to 5/4 (decimal: 1.250000). An answer bigger than one is normal here: 2/3 fits into 5/6 once with a quarter of itself left over.
The answer is 3/10 (decimal: 0.300000). A standard floating-point calculator returns 0.30000000000000004 for the same sum, because neither 0.1 nor 0.2 can be stored exactly in binary. Treating the inputs as 1/10 and 2/10 avoids that drift entirely.
Subtracting 1/8 from 0.125 gives 0 (decimal: 0.000000); a whole number is printed without a denominator. The opposite case matters more: 1/3000000 is a real, non-zero fraction whose decimal still shows as 0.000000, because six places cannot reach it. Trust the fraction, not the decimal.
Mixed-number notation is not accepted. Entering 1 3/4 returns an error, because the space is not an operation. Convert it first: multiply the whole number by the denominator and add the numerator, so 1 3/4 becomes (1 × 4 + 3)/4 = 7/4, and 2 5/8 becomes 21/8. Adding 21/8 and 1/6 then returns 67/24 (decimal: 2.791667), which is 2 and 19/24 if you convert it back by hand.
A minus sign may sit on the numerator or the denominator, and the result is the same: −3/4 and 3/−4 both behave as negative three quarters. Adding either to 1/2 gives −1/4 (decimal: −0.250000). The sign is always moved onto the numerator in the answer, so a negative denominator is never printed, and two negatives cancel as usual: −1/2 times −1/3 is 1/6. A decimal denominator is not allowed either, so rewrite 1/0.5 as 2 before entering it.
Two values and one operation per calculation. There is no expression entry, so 1/2 + 1/3 + 1/4 takes two passes, retyping the first answer. The tool does not convert answers to mixed numbers, does not show a lowest-common-denominator working, and does not handle percentages, algebra, repeating-decimal notation or roots. The decimal line is a display approximation at six places and may round a small non-zero value to 0.000000. Nothing is stored: editing an input clears the answer, and reloading starts over.
Yes. Both the numerator and the denominator are divided by their greatest common divisor before anything is printed, and that happens on the inputs too, so 4/8 is treated as 1/2 from the start. If the denominator reduces to 1, the answer is shown as a plain whole number.
Yes, and there is no need to convert it. Improper fractions are the easier form to calculate with; 11/4 minus 1 returns 7/4.
You get Cannot divide by zero. and no result. That covers a zero denominator in either input and a second value of zero when the operation is division.
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Reviewed October 1, 2026. Calculation methods and corrections.