Subtract Fractions Calculator
To subtract fractions, find a common denominator, subtract the numerators, and simplify the result. This free subtract fractions calculator handles simple fractions, different denominators, and mixed numbers — showing complete step-by-step solutions for every problem so you can learn the process as you go.
Subtract Fractions Calculator
How Do You Subtract Fractions Step by Step?
To subtract fractions, make the denominators the same, subtract the numerators, keep the common denominator, and simplify. This rule applies to every fraction subtraction problem — whether the denominators match or not.
Subtracting fractions follows the same core principle as adding fractions: the denominators must match before you can work with the numerators. The process breaks down into three scenarios, each explained below.
What If the Denominators Are Already the Same?
When the denominators are already equal, subtract the second numerator from the first and keep the denominator unchanged. For example, 5/8 − 3/8 = 2/8, which simplifies to 1/4. This is the simplest case of fraction subtraction. If you need help reducing, try the Simplify Fractions Calculator.
How Do You Subtract Fractions with Different Denominators?
When denominators differ, you must find the least common denominator (LCD) first, convert each fraction to an equivalent fraction with that LCD, and then subtract the numerators. Our LCD Calculator can help you find the least common denominator quickly.
For example, to solve 3/4 − 1/6: the LCD of 4 and 6 is 12. Convert each fraction — 3/4 becomes 9/12, and 1/6 becomes 2/12. Subtract the numerators: 9/12 − 2/12 = 7/12. Since 7 and 12 share no common factors, 7/12 is the final answer.
How Do You Subtract Mixed Numbers (and When Do You Borrow)?
To subtract mixed numbers, convert each mixed number to an improper fraction, perform the subtraction as shown above, then convert the result back to a mixed number if needed. When the fraction part of the first mixed number is smaller than the second, you must "borrow" 1 from the whole number — the calculator above handles borrowing automatically.
For a deeper explanation with more examples, see our full guide on How to Subtract Fractions. You can also practice with the Mixed Number Calculator.
What Are Some Examples of Subtracting Fractions?
The denominators are already the same (10), so subtract the numerators directly:
7 − 3 = 4Write the result over the common denominator: 4/10. Now simplify by dividing both by 2:
4/10 = 2/5Find the LCD of 6 and 4, which is 12. Convert each fraction:
5/6 = 10/12 (×2) 1/4 = 3/12 (×3)Subtract the numerators:
10/12 − 3/12 = 7/127/12 is already in simplest form.
Convert to improper fractions:
3 1/4 = 13/4 1 2/3 = 5/3Find the LCD of 4 and 3, which is 12:
13/4 = 39/12 (×3) 5/3 = 20/12 (×4)Subtract:
39/12 − 20/12 = 19/12Convert back to a mixed number: 19/12 = 1 7/12.
Can You Solve These Fraction Subtraction Problems?
Try these on your own, then click "Show Answer" to check your work.
Frequently Asked Questions About Subtracting Fractions
The three steps are: first, find a common denominator (the LCD) for both fractions. Second, convert each fraction to an equivalent fraction with that common denominator. Third, subtract the numerators, keep the denominator, and simplify the result to its lowest terms.
Find the least common denominator (LCD) of both fractions, convert each fraction to an equivalent fraction with that LCD, then subtract the numerators and keep the common denominator. Simplify the result if possible. For example, 3/4 − 1/6 requires an LCD of 12, giving 9/12 − 2/12 = 7/12.
Yes, and it is the simplest case. When both fractions share the same denominator, subtract the second numerator from the first and write the result over the common denominator. For example, 7/9 − 2/9 = 5/9. No conversion is needed.
Convert each mixed number to an improper fraction, find a common denominator, subtract the numerators, and then convert the result back to a mixed number. For example, 3 1/4 − 1 2/3 becomes 13/4 − 5/3 = 39/12 − 20/12 = 19/12, which equals 1 7/12.
Borrowing happens when the fraction part of the first mixed number is smaller than the fraction part of the second. You take 1 from the whole number and add it to the fraction as a full unit (e.g., converting 4 1/5 into 3 6/5) so the subtraction can proceed. This is similar to borrowing in whole-number subtraction.
Yes. Toggle on "Mixed numbers" mode, then enter the whole number, numerator, and denominator for each mixed number. The calculator converts them to improper fractions, performs the subtraction, handles any borrowing automatically, and shows the full step-by-step work.
A negative result occurs when the second fraction is larger than the first. The calculator handles this correctly and displays the negative sign clearly. For example, 1/4 − 3/4 = −2/4, which simplifies to −1/2.
No. The calculator automatically simplifies every answer to its lowest terms by dividing the numerator and denominator by their greatest common factor. It also shows you the simplification step so you can learn how to reduce fractions on your own.
Subtracting fractions involves only numerators and denominators. Mixed numbers also include a whole number part, so you must first convert them to improper fractions before subtracting, or subtract whole numbers and fractions separately — which sometimes requires borrowing from the whole number.
Denominators represent the size of each piece. You cannot subtract pieces of different sizes directly — just like you cannot subtract inches from centimeters without converting. A common denominator ensures both fractions describe equal-sized parts so the numerators can be subtracted meaningfully.