Subtracting fractions is easier than you think! The key is finding a common denominator. Below, you’ll find clear explanations, examples, and a calculator to help verify your calculations.
The denominators must be the same to subtract fractions—that’s the fundamental rule of fraction subtraction!
Fraction subtraction is useful in everyday life—from cooking recipes to budgeting.
Subtracting fractions relies on a simple principle: the denominators must be the same to subtract the numerators. If the fractions have different denominators, you need to find a common denominator first.
When denominators are the same:
\( \large \frac{5}{7} - \frac{2}{7} = \frac{5 - 2}{7} = \frac{3}{7} \)
Subtract only the numerators (top numbers), while the denominator (bottom number) stays the same.
When denominators are different:
You need to find a common denominator:
\( \large \frac{3}{4} - \frac{1}{3} \)
Find the common denominator (12), convert the fractions, and subtract the numerators.
Formula for subtracting fractions with different denominators:
\( \huge \frac{a}{b} - \frac{c}{d} = \frac{a \times d - c \times b}{b \times d} \)
Check the denominators—are they the same or different?
Find a common denominator if they’re different (usually the LCM).
Convert the fractions to the common denominator.
Subtract the numerators and keep the common denominator.
Simplify the result to its simplest form.
To find a common denominator:
Example: For fractions \( \large \frac{2}{3} \) and \( \large \frac{3}{5} \), LCM(3, 5) = 15
Example 1: Fractions with the same denominator
Example 2: Fractions with different denominators
Example 3: Subtraction with a negative result
Don’t subtract the denominators!
Wrong: \( \large \frac{3}{4} - \frac{1}{2} = \frac{3-1}{4-2} = \frac{2}{2} = 1 \) ❌
Correct: \( \large \frac{3}{4} - \frac{1}{2} = \frac{6}{8} - \frac{4}{8} = \frac{2}{8} = \frac{1}{4} \) ✓
Incorrect common denominator
Always find the LCM of the denominators, don’t just multiply them (unless that’s the LCM).
Incorrect fraction conversion
Remember to multiply both numerator and denominator by the same number.
Not simplifying the result
Always check if the result can be simplified by dividing numerator and denominator by their common factor.
Issues with negative signs
If you subtract a larger fraction from a smaller one, the result is negative—don’t forget the minus sign!
Practice regularly
Consistent practice is key. Start with simple examples and progress to more complex ones.
Visualize fractions
Drawing fractions on paper (e.g., as parts of a circle or rectangle) helps understand their meaning.
Break it down
Divide the problem into smaller steps—find the common denominator, convert fractions, subtract numerators.
Check your work
Use a fraction calculator to verify your answers and identify mistakes.
Task 1: Subtract fractions with the same denominator
Task 2: Subtract fractions with different denominators
Task 3: Real-world applications
Practice with our calculator to solidify your fraction subtraction skills!
Back to the Calculator