Fraction Calculator

This calculator adds, subtracts, multiplies and divides fractions and mixed numbers, and gives the answer in lowest terms, as a mixed number, as a decimal and as a percentage. It also simplifies a single fraction and turns a decimal into a fraction, including repeating decimals such as 0.333… The arithmetic is done on whole numbers of any length, so nothing is rounded: 1/3 + 1/6 is exactly 1/2, and 0.1 + 0.2 is exactly 3/10.

1. Choose "Two fractions" to work with two numbers, or "Simplify or convert" for one.
2. Type each number as 3/4, as a mixed number such as 1 1/2, as a whole number, or as a decimal such as 0.75.
3. For a repeating decimal, put the part that repeats in brackets: 0.(3) is 0.333…, and 0.1(6) is 0.1666…
4. Pick +, −, × or ÷. The answer updates as you type, with the working in the notes under it.

• Each number can be up to 60 characters long. Inside that, the top and bottom of a fraction can be as large as you like, and the answer stays exact.
• A space separates the whole part of a mixed number from its fraction, so "1 1/2" is one and a half. "11/2" is eleven halves.
• A negative mixed number is negative as a whole: −2 3/8 means −(2 + 3/8), which is −19/8, as it is in maths books.
• The exact decimal is worked out to 200 places. A fraction whose repeating block is longer than that (1/9973 repeats every 9,972 digits) ends with "…" instead of brackets.
• Everything is worked out in this page, on your device. Nothing you type is sent anywhere or saved, and the calculator works offline once the page has loaded.

Bring them to a common denominator first. For 1/2 + 1/3, multiply across to get 3/6 + 2/6, which is 5/6. The calculator multiplies the denominators together and then reduces the answer, which always works and gives the same result as finding the lowest common denominator first.

Write the decimal over a power of ten and simplify: 0.375 is 375/1000, and dividing both parts by 125 gives 3/8. Choose "Simplify or convert" and type the decimal; the calculator does the dividing for you.

Type it with the repeating part in brackets. 0.(3) becomes 1/3, 0.1(6) becomes 1/6, and 0.(142857) becomes 1/7. The method is the one taught in school: the repeating block over as many 9s as it has digits, then simplified.

Because 0.999… repeating is exactly 1, not a number just below it. One third is 0.333…, three thirds are 0.999…, and three thirds are also 1.

A whole number and a proper fraction written together, such as 1 3/4 for seven quarters. The calculator shows the mixed form whenever the answer is more than 1 and not whole.