Percentage Calculator
Three common percentage calculations in one place — updated instantly as you type.
What is X% of Y?
= 30
X is what percent of Y?
= 20%
Percentage change from X to Y
= 20% increase
How it works
Pick the calculation you need
Basic percentage, share of a total, or the change between two numbers.
Type your numbers
Each result updates instantly as you type — no button to press.
Read your answer
The result is labeled clearly, including whether a change is an increase or a decrease.
What people use a percentage calculator for
Percentages come up constantly in everyday numbers — here are a few common cases.
Discounts & sales
Tips & splitting bills
Comparing changes
Grades & scores
Growth & reports
Frequently asked questions
How do I calculate what X% of Y is?
Divide X by 100 and multiply the result by Y. For example, 20% of 150 is (20/100) × 150 = 30. The first calculator on this page does that instantly.
How do I find what percent one number is of another?
Divide the first number by the second and multiply by 100. For example, 30 is what percent of 150? (30/150) × 100 = 20%. Use the second calculator for this.
How is percentage increase or decrease calculated?
Subtract the original value from the new value, divide that difference by the original value, then multiply by 100. A positive result is an increase, a negative result is a decrease.
Why do percentage changes look different going up versus down?
Because the base changes. Going from 100 to 150 is a 50% increase, but going back from 150 to 100 is a 33.3% decrease — the same 50-point difference is a different percentage of a different starting number.
Is this percentage calculator free to use?
Yes, completely free, with no account or sign-up, and it runs entirely in your browser.