Add or subtract two fractions with different denominators. See the LCD, step-by-step simplification, mixed number form, and decimal equivalent with a common-denominators reference table.
The **Adding and Subtracting Fractions Calculator** makes working with fractions effortless. Enter any two fractions — even with completely different denominators — choose addition or subtraction, and the tool walks you through every step: finding the Least Common Denominator (LCD), converting each fraction, performing the operation, and simplifying the result.
Fractions are everywhere — recipes, measurements, financial splits, statistics, and standardised tests. Yet adding or subtracting fractions with unlike denominators trips up students and adults alike because it requires finding a common denominator first. This calculator automates the tedious arithmetic while still showing the work, so you learn (or verify) the process rather than blindly trusting a number.
The output includes the result as an improper fraction, a simplified fraction, a mixed number (when applicable), and a decimal equivalent — all at once. A step-by-step breakdown mirrors what you would write on paper: find the LCD, multiply numerator and denominator, add or subtract the numerators, then reduce by the GCD.
Eight preset buttons load classic textbook problems instantly, and a reference table of common denominators (2–12) lets you quickly see LCD values for popular fraction pairs. Whether you are a student checking homework, a teacher preparing examples, or a cook doubling a recipe with ¾ cups and ⅔ cups, this tool has you covered.
This calculator is useful when you need more than just the final fraction. It shows the exact Least Common Denominator used for the two denominators, the converted equivalent fractions, the unsimplified result, the simplified answer, the mixed-number form, and the decimal value. That makes it practical for homework checks, recipe scaling, measurement problems, and any situation where you need to confirm each algebra step instead of only seeing the end result.
It is also helpful because the operation toggle lets you switch between addition and subtraction without re-entering the fractions, while the preset examples, visual fraction bars, step list, and common-denominator table make it easy to compare cases such as like denominators versus unlike denominators. If you are learning why common denominators matter, this layout mirrors the real paper method closely enough to study from.
a/b ± c/d = (a·(LCD/b) ± c·(LCD/d)) / LCD, where LCD = LCM(b, d). Simplify by dividing numerator and denominator by GCD(numerator, LCD).
Result: 1/2 + 1/3 = 5/6, using an LCD of 6.
Convert 1/2 to 3/6 and 1/3 to 2/6. Then add the numerators to get 5 while keeping the denominator 6.
The component takes two fractions, finds the Least Common Denominator with the least common multiple of the two denominators, and then computes the multiplier needed for each fraction. Those converted numerators are displayed in the working steps so you can see exactly how a fraction like $ rac{1}{2}$ becomes $ rac{3}{6}$ before the numerators are combined. This is the main place students usually make mistakes by adding denominators directly, and the calculator avoids that by exposing every intermediate value.
Because the tool also reports the raw result before simplification, you can compare the unsimplified fraction with the reduced one. That is especially useful when checking classwork or explaining why a result such as $ rac{10}{12}$ should be reduced to $ rac{5}{6}$ using the GCD.
The output cards are built for different ways of reading the same answer. The simplified fraction is the exact rational result, the mixed number helps when the answer is greater than one, and the decimal gives a quick magnitude check. The fraction-bar visual makes it easier to see whether subtraction should leave a smaller positive result or a negative one, and the common LCD reference table supports quick practice with familiar denominator pairs like 2 and 3 or 8 and 12.
Taken together, these features make the calculator more than a fraction adder. It is a worked-example tool for two-fraction arithmetic, whether you are verifying textbook exercises, combining measured quantities, or demonstrating the difference between raw and simplified answers.
Find the LCD, convert both fractions to that denominator, add the numerators, and simplify. For example, 1/2 + 1/3 = 3/6 + 2/6 = 5/6.
Yes. Convert mixed numbers to improper fractions (or handle whole parts separately), find a common denominator, perform the operations, and simplify the result.
When denominators are the same, add or subtract only the numerators and keep the shared denominator: a/c +/- b/c = (a +/- b)/c. You do not add the denominators because the fractional parts are already measured in the same-sized pieces.
Convert both fractions to a common denominator first, then subtract the numerators while keeping the denominator the same. For example, 3/4 − 1/3 = 9/12 − 4/12 = 5/12.
Any common multiple of the denominators works as a common denominator, but the LCD is the smallest one. Using the LCD keeps the numbers smaller and reduces the need for simplification later.
Yes, subtracting a larger fraction from a smaller one gives a negative result. For example, 1/4 − 3/4 = −2/4 = −1/2.