Math
Subtracting Fractions Calculator
Subtract one fraction, mixed number, whole number, or decimal from another.
The calculator finds the least common denominator from prime factors, rewrites both fractions, shows borrowing when a mixed-number subtraction needs it, and reports the simplified difference as a fraction, mixed number, decimal, and percent with a fraction-strip picture.
Type a fraction (3/4), a mixed number (2 1/3), a whole number, or a decimal (1.75). Repeating decimals work too: 0.(3).
The value being taken away.
Try an example
Result
Difference (simplified)
—
- Mixed number
- —
- Decimal
- —
- Percent
- —
- Least common denominator
- —
Student quick launch
Grade planning, algebra checks, and formulas students reach for most.
Study path
Use this calculator with
Follow these when you want the formula behind the answer, a short lesson, or nearby tools in the same topic.
How to subtract fractions
Subtracting fractions works exactly like adding them: both fractions need the same The bottom number of a fraction; it says how many equal parts make one whole. first. Find the The smallest bottom number two fractions can share so you can add or compare them., rewrite each fraction over it, subtract the The top number of a fraction; it counts how many parts you have., keep the denominator, and simplify.
Subtracting mixed numbers with borrowing
When you subtract A whole number written next to a fraction, like 2 1/3. column-style, the fraction part on top is sometimes smaller than the one below it. Borrow one whole from the whole-number part and add it to the fraction as denominator/denominator. For 3 1/4 - 1 3/4, borrow to get 2 5/4, then subtract: 2 - 1 = 1 and 5/4 - 3/4 = 2/4, giving 1 2/4 = 1 1/2. The calculator shows this regrouping whenever both inputs are positive mixed numbers.
The other reliable method is to convert both mixed numbers to A fraction whose top number is at least as big as its bottom number, like 7/3. and subtract those. Both methods give the same answer; the improper-fraction route never needs borrowing but produces larger numerators.
Negative answers
If the second fraction is larger than the first, the difference is negative. 1/4 - 3/4 = -2/4 = -1/2. A negative fraction is written with the sign in front of the whole fraction, and the strip picture shows the result strip lightly shaded to signal a negative amount.
| Situation | Example | Result |
|---|---|---|
| Same denominator | 5/8 - 3/8 | 2/8 = 1/4 |
| Unlike denominators | 2/3 - 1/4 | 8/12 - 3/12 = 5/12 |
| Mixed with borrowing | 3 1/4 - 1 3/4 | 2 5/4 - 1 3/4 = 1 2/4 = 1 1/2 |
| Second larger | 1/4 - 3/4 | -2/4 = -1/2 |
| Equal fractions | 2/6 - 1/3 | 0 |
How to use it
- Type the starting fraction or mixed number in the first box and the amount to subtract in the second box.
- Mixed numbers use a space (3 1/4); negative values take a leading minus sign (-3 1/4); decimals such as 1.75 and repeating decimals such as 0.(3) are converted exactly.
- Read the simplified difference, mixed number, and decimal in the panel.
- Open Show the work for the LCD, rewritten fractions, borrowing (when both inputs are positive mixed numbers), and the simplification.
How to read the answer
A positive difference means the first fraction is larger; a negative difference means the second one is. Zero means they are equal. The mixed-number form shows wholes plus a proper fraction, and the decimal and percent give the same value in other notations.
Common mistakes and edge cases
- Do not subtract denominators. 5/8 - 3/8 is 2/8, not 2/0.
- When borrowing, add the whole denominator to the numerator: 3 1/4 becomes 2 5/4, not 2 2/4.
- Keep the order. Subtraction is not commutative: 3/4 - 1/4 and 1/4 - 3/4 have opposite signs.
- A negative mixed number applies its sign to the whole value: -2 1/3 means -(2 + 1/3) = -7/3.
- Simplify at the end. 2/4 and 1/2 are the same amount, but the simplified form is expected in most classrooms.
Worked examples
Mixed numbers with borrowing
3 1/4 - 1 3/4
Difference (simplified)
3/2
Unlike denominators
2/3 - 1/4
Difference (simplified)
5/12
Negative answer
1/4 - 3/4
Difference (simplified)
-1/2
Equal fractions
2/6 - 1/3 = 0
Difference (simplified)
0
Whole minus fraction
5 - 2/3
Difference (simplified)
13/3
Decimal minus fraction
1.5 - 3/8
Difference (simplified)
9/8
Subtracting a negative
1/2 - (-1/3)
Difference (simplified)
5/6
Zero denominator
1/2 - 3/0 is undefined
Difference (simplified)
Error
Frequently asked questions
How do you subtract fractions with different denominators?+
Find the least common denominator, rewrite both fractions over it, subtract the numerators, and simplify. 2/3 - 1/4 becomes 8/12 - 3/12 = 5/12.
How do you subtract mixed numbers when the top fraction is smaller?+
Borrow one whole from the whole-number part and add it to the fraction as denominator/denominator. 3 1/4 becomes 2 5/4, and then 5/4 - 3/4 works without a negative fraction part.
Can the answer be negative?+
Yes. When the second value is larger than the first, the difference is negative. The calculator writes the sign in front of the whole fraction, such as -1/2.
Is it better to convert mixed numbers to improper fractions first?+
Both methods are correct. Converting to improper fractions avoids borrowing but creates larger numbers. The calculator shows borrowing when both inputs are positive mixed numbers and the improper-fraction method otherwise.
What does it mean if the difference is 0?+
The two fractions are equivalent, even if they look different. For example 2/6 and 1/3 are the same value.
Can I subtract a decimal from a fraction?+
Yes. Decimals are converted to exact fractions first. 1.5 - 3/8 becomes 3/2 - 3/8 = 12/8 - 3/8 = 9/8.
About this calculator
- Written by
- mathcheck editorial team
- Last reviewed
- September 4, 2026
Method
- Uses the values entered by the user and stable formulas documented on the page.
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Last updated: September 4, 2026