Subtracting Fractions Calculator
Subtract one fraction from another, reduced to lowest terms.
Subtraction works exactly like addition: match the denominators, then subtract the numerators.
How the subtracting fractions calculator works
Subtraction works exactly like addition: match the denominators, then subtract the numerators. 3/4 − 1/6 becomes 18/24 − 4/24 = 14/24, which reduces to 7/12.
The answer goes negative whenever the second fraction is larger, and the minus sign is carried on the numerator.
Formula: a/b + c/d = (ad + cb) / bd; a/b × c/d = ac / bd; a/b ÷ c/d = ad / bc
Worked examples
| Inputs | Answer in lowest terms | Note |
|---|---|---|
| 3/4 − 1/6 | 7/12 | 7/12 |
| A negative result | -1/6 | −1/6 |
| Subtracting to nothing | 0 | 0 |
FAQFrequently asked questions
How do I subtract fractions?
Give them a common denominator, subtract the numerators, then reduce.
What is 3/4 − 1/6?
7/12.
Can the answer be negative?
Yes, whenever the second fraction is bigger. The sign sits on the numerator.
Do I subtract the denominators?
No. The denominators only tell you the size of the pieces; once they match, only the numerators change.
How do I subtract mixed numbers?
Convert both to improper fractions first — it avoids having to borrow from the whole number.
Where these figures come from
- NIST Digital Library of Mathematical Functions — reference definitions for elementary and special functions
- Wolfram MathWorld — definitions and formulas for every topic on this page
- NIST/SEMATECH e-Handbook of Statistical Methods — the statistical formulas (mean, variance, z, confidence intervals, sample size)
- Common Core State Standards — Mathematics — the terms and methods taught in US schools
Last checked: September 2026. Formulas are fixed by mathematics and do not change with tax years or regulations.