Written by Sarah Mitchell · Reviewed by Jane Smith · July 18, 2026
Add, subtract, multiply, and divide fractions with simplified results.
Enter fractions and click Calculate.
This tool adds, subtracts, multiplies, and divides two fractions, including values with a whole-number part. It returns the answer as a simplified fraction, converts it to a mixed number when the numerator outgrows the denominator, and shows the decimal equivalent. All the work happens in your browser with no data sent anywhere.
Fractions with different denominators cannot be combined directly. The tool first turns any mixed number into an improper fraction using whole x denominator + numerator. It then finds the least common multiple of the two denominators, scales both fractions so they share it, adds or subtracts the numerators, and reduces the result by dividing out the greatest common divisor. If the final numerator is at least as large as the denominator, the answer is rewritten as a mixed number.
The denominators 4 and 6 have a least common multiple of 12. Scaling gives 3/4 = 9/12 and 1/6 = 2/12, so the sum is 11/12. That fraction is already in lowest terms, and the decimal view shows 0.9167. Adding the numerators without the common-denominator step, 3 + 1 over 4 + 6, would wrongly produce 4/10.
Multiplying is direct: numerators multiply and denominators multiply, then the product is reduced. For example, 3/4 x 1/6 = 3/24, which simplifies to 1/8, or 0.125. Division flips the second fraction and multiplies: 3/4 divided by 1/6 becomes 3/4 x 6/1 = 18/4, which reduces to 9/2 and displays as the mixed number 4 1/2, equal to 4.5.
A mixed input like 2 1/2 is converted to 5/2 before any operation. Adding 2 1/2 and 1 1/3 gives 5/2 + 4/3. With a common denominator of 6 that becomes 15/6 + 8/6 = 23/6, and since 23 exceeds 6, the tool reports the answer as 3 5/6.
A denominator must be at least 1; the tool rejects anything lower rather than inventing an undefined value. Dividing by a fraction whose numerator is zero, such as 1/2 divided by 0/5, triggers an error because it means division by zero. Negative fractions are handled by carrying the sign on the numerator, so subtracting a negative fraction behaves like addition.
Because the denominators describe different-sized pieces. Halves and sixths are not the same unit, so their counts cannot be summed until both are expressed in a shared unit, which is the least common multiple.
It finds the smallest denominator both fractions can be scaled to, keeping the numbers small and the result easier to reduce afterward.
Whenever the absolute value of the numerator is at least as large as the denominator, such as 9/2 becoming 4 1/2. Otherwise it stays as a proper fraction.
The tool shows an error. Dividing by zero is undefined in arithmetic, and the calculator refuses to display a meaningless result.
Yes. The greatest common divisor is factored out of every result, so 3/24 appears as 1/8 and 18/4 appears as 9/2.
Yes. Each side accepts a whole part plus a numerator and denominator, and both are normalized to improper fractions before the operation runs.
Fractions are the right choice when exactness matters: scaling a recipe, splitting a bill among three people, or working in halves and eighths on a measuring tape. A decimal like 0.3333 rounds off 1/3, while the fraction keeps the value exact. For money and most measurements, decimals are more natural, but any time the answer must be a precise ratio, use the fraction view.
When the reduced result has a numerator larger than its denominator, the tool splits it into a whole part and a remaining proper fraction. Nine halves become four and one half rather than an unwieldy nine-over-two. The whole part comes from dividing the numerator by the denominator, and the remainder becomes the new numerator over the unchanged denominator. This layout is easier to read on a tape measure, a recipe scale, or a woodworking mark.
To tell which of two fractions is larger, cross-multiply: for a/b and c/d, compare a times d against c times b. The trick works even for awkward pairs like sevenths and elevenths, where finding a shared bottom number by hand is slow. The same reasoning explains why the calculator never adds numerators directly: halves and quarters count pieces of different sizes, and only a common unit makes their totals comparable.
The decimal output reaches six places, which is plenty for construction, cooking, or splitting a payment. A value like one-third never terminates, so the display cuts the repeating digits instead of attempting to show every one. When the decimal ends in zeros, the tool strips the trailing digits, so three-quarters appears as 0.75 rather than 0.750000. For exact arithmetic, trust the fraction form; for a number you can paste into a spreadsheet or another calculator, copy the decimal.
A negative fraction keeps its sign on the numerator, so subtracting a negative value behaves like addition. For example, 1/2 minus negative 1/4 equals 3/4. The denominator itself must stay positive, and the tool enforces that by requiring the bottom input to be at least one. If you see a result with a minus sign in an unexpected place, check whether you entered a negative numerator by accident.
The strip between the two fractions holds four operators: plus, minus, times, and divided by. Clicking one marks it as the active operator for the calculation. The numerator fields accept any whole number down to -9999, while the denominators start at one and allow any positive integer, so a zero denominator cannot be entered.
Each side also takes an optional whole part, so a value like 2 1/2 is typed as whole 2 with numerator 1 over denominator 2. The tool converts that mixed form into the improper fraction 5/2 before the operation runs, which keeps the arithmetic consistent for every operator and every pair of inputs.