Fraction Guide and Calculator
Least Common Denominator Calculator
Find the least common denominator of two or more fractions. Enter fractions, review the LCD, and use the equivalent forms when adding, subtracting, or comparing fractions.
A worked LCD example
The LCD is the least common multiple of the denominators. For denominators 4 and 6, the multiples meet at 12, so 12 is the least common denominator.
How this page connects to fraction work
For 3/4 and 5/6, the LCD is 12. Multiply 3/4 by 3 to get 9/12 and 5/6 by 2 to get 10/12. Link to the LCD calculator when you need to test additional denominators.
Frequently Asked Questions
Why do fractions need a common denominator?
Fractions must use the same denominator before their numerators can be added or subtracted directly.
Can I use the LCD calculator for more than two fractions?
Yes. Enter the denominators or fractions and the calculator finds the least shared denominator.