Fraction Calculator — Add, Subtract, Multiply, Divide
Two fractions, four operations. Accepts mixed numbers (2 1/3), improper fractions (7/3), and decimals (0.75). Shows the simplified answer, mixed form, decimal, and the worked-out steps.
What is fraction calculator?
A fraction is a number written as one integer divided by another — the numerator over the denominator. Fractions are how most students first encounter arithmetic that doesn’t fit cleanly on a number line: 1/2 isn’t a whole number, but it’s a precise value with a clear meaning. This calculator handles the four basic operations on two fractions and accepts whichever form you have in hand: a plain fraction like 5/8, an improper one like 7/3, a mixed number like 2 1/3, or a decimal like 0.75.
The arithmetic is straightforward in principle. Addition and subtraction with different denominators require a common denominator first; multiplication multiplies numerators and denominators separately; division flips the second fraction and multiplies. What makes fractions error-prone for students is the bookkeeping — finding common denominators, simplifying results, converting between mixed and improper forms. This calculator does all of that automatically and shows the worked-out line so you can see (and replicate on paper) the intermediate step you’re expected to demonstrate.
A practical note on inputs. The parser is strict in one specific way: a mixed number requires a single space between the whole part and the fraction part (2 1/3, not 21/3). Decimal inputs are converted to fractions exactly — 0.75 becomes 3/4, but 0.333 becomes 333/1000, not 1/3. If you want the exact fractional value, type it as a fraction. Component values are capped at one million to keep the arithmetic exact in JavaScript’s number type; if your problem genuinely needs larger numerators, reduce by hand first.
Privacy is the final detail. Every calculation runs locally in your browser. The values you type never leave your device — there is no server, no API call, no analytics on the inputs. The page does carry a third-party display ad slot (which is how the site stays free), but the ad has no access to your fractions.
When to use a fraction calculator
- Homework help — adding fractions with different denominators — Type the two fractions, pick +, and read the simplified answer with the worked-out steps below. Useful for double-checking that 1/2 + 1/3 = 5/6 and seeing the common-denominator step (3/6 + 2/6) you may be expected to show.
- Recipes — scaling a recipe up or down — If a recipe calls for 2 1/3 cups of flour and you want to triple it, type 2 1/3 × 3 to see 7 cups. If you want half of 3/4 cup, enter 3/4 × 1/2 and read 3/8.
- Construction and woodworking — adding measurements — Measurements on a tape measure are usually fractions of an inch. Adding 5 7/8 + 2 3/16 by hand is fussy; type the two values, pick +, and read the simplified result plus its decimal equivalent.
- Comparing fractions via their decimal values — The decimal output makes side-by-side comparison trivial. 5/8 vs 0.6? Type 5/8 and any operator with a 0 second operand isn't useful — instead, enter 5/8 − 0 to read the decimal (0.625) and see it's slightly larger than 0.6.
- Sanity-checking a hand calculation — When you've worked out a fraction problem on paper, type the two operands and the operator to verify the answer. The calculator shows both the simplified fraction and the mixed-number form, so you can match whichever form the textbook expects.
How to use the Fraction Calculator — Add, Subtract, Multiply, Divide
- Type the first fraction — Use the Fraction A input. Accepted formats are proper fractions (5/8), improper fractions (7/3), mixed numbers (2 1/3, with a space between the whole part and the fraction part), decimals (0.75), and plain integers (5). A leading minus sign is allowed.
- Pick the operator — Choose +, −, ×, or ÷ from the operator dropdown. The default is +. Division by a fraction with a zero numerator is rejected with a clear error message.
- Type the second fraction and read the result — The result panel updates as you type. The headline shows the simplified fraction; below it, the mixed-number form (if the result is improper) and the decimal equivalent (rounded to four decimal places). The bottom line shows the worked-out form (a/b op c/d = result ≈ decimal). Tap Copy to put that line on your clipboard.
Worked examples
Adding fractions with different denominators
Input: 1/2 + 1/3
Output: 5/6 (≈ 0.8333)Common denominator is 6: 1/2 = 3/6 and 1/3 = 2/6, so 3/6 + 2/6 = 5/6.
Mixed number arithmetic
Input: 2 1/3 × 3
Output: 7 (≈ 7)2 1/3 is the same as 7/3. Multiplying by 3 gives 21/3 = 7.
Subtraction with a negative result
Input: 1/4 − 1/2
Output: -1/4 (≈ -0.25)Negative results are shown with a leading minus sign; the mixed-number form keeps the sign on the whole part when the result is improper.
Division of fractions
Input: 3/4 ÷ 1/2
Output: 3/2 (mixed: 1 1/2, ≈ 1.5)Dividing by a fraction is the same as multiplying by its reciprocal: 3/4 × 2/1 = 6/4 = 3/2.
Decimal input converted to a fraction
Input: 0.75 + 1/8
Output: 7/8 (≈ 0.875)0.75 is parsed as 75/100, simplified to 3/4. Then 3/4 + 1/8 = 6/8 + 1/8 = 7/8.
Frequently asked questions
How do I enter a mixed number?
2 1/3 for two and one-third. The space is required; 21/3 is parsed as the improper fraction twenty-one thirds. Negative mixed numbers take a leading minus sign on the whole part: -2 1/3.Can I enter decimals?
0.75 is parsed as 75/100 and simplified to 3/4. Be aware that decimals like 0.333 are parsed as 333/1000, not as 1/3 — type 1/3 directly if you want that exact value.Does the result always show in lowest terms?
4/8 becomes 1/2; 10/4 becomes 5/2.What is the difference between a proper, improper, and mixed fraction?
3/4). An improper fraction's numerator is equal to or larger than its denominator (7/3). A mixed number is the same value written as a whole part plus a proper fraction (2 1/3 = 7/3). The calculator shows both forms in the result panel.Why is there a limit on how large my numbers can be?
How do I divide one fraction by another?
a/b by c/d is the same as multiplying by the reciprocal: a/b × d/c. The result is then simplified. Division by zero (a second operand of 0) is rejected with an explicit error.Why does the calculator show the decimal value too?
5/8 = 0.625 is easier to compare against another value than the fraction form is. Second, real-world measurements (a digital scale, a CAD program) often want the decimal value, so we show both for free. The decimal is rounded to four places with trailing zeros stripped.