Calculators
Percentage Calculator
Free percentage calculator for what is X% of Y, X is what percent of Y, percentage increase and percentage decrease.
What is X% of Y?
X% of Y
15% of 240
36
X is what percent of Y?
X is what percent of Y
45 is this percent of 180
25%
Percentage increase / decrease
Change
Increase
25%
Need original price, sale price or how much you save? Use the Discount Calculator.
About this tool
This percentage calculator has three modes. The first answers what is X% of Y (15% of 240). The second answers X is what percent of Y (45 of 180). The third is percentage increase or percentage decrease between two numbers. For original price, sale price and how much you save, use the Discount Calculator instead.
How to use
- What is X% of Y?: enter the percent in X and the amount in Y.
- X is what percent of Y?: enter the part in X and the whole in Y. Y cannot be zero.
- Percentage increase or decrease: enter the starting value in From and the new value in To. From cannot be zero.
How to find X% of Y
Amount = (X ÷ 100) × Y. Example: 15% of 240 = 0.15 × 240 = 36. Sales tax, tips and “20% off the listed price” all use this form.
How to find what percent X is of Y
Percent = (X ÷ Y) × 100. Example: 45 is 25% of 180 because 45 ÷ 180 = 0.25. Exam marks (32 out of 40) use this formula, not “32% of 40”.
How percentage increase works
((new − original) ÷ |original|) × 100. From 80 to 100 is a 25% increase. The first card’s 15% of 240 is a share of one number; this card compares two numbers.
How percentage decrease works
The same change formula, with a negative result when the new value is smaller. From 100 to 80 is a 20% decrease — not the same size as the 25% rise the other way.
Frequently asked questions
What is the difference between percentage change and percentage points?+
Percentage points measure the absolute arithmetic difference between two percentage values (e.g., an interest rate moving from 10% to 15% increases by 5 percentage points: 15 − 10 = 5). Percentage change measures the relative growth: ((15 − 10) ÷ 10) × 100 = 50% relative increase. Confusing the two is a frequent error in finance and statistics.
Why cannot the denominator or starting value be zero?+
Division by zero is mathematically undefined. A change from 0 to any non-zero number represents an infinite ratio rather than a finite percentage change.
Should I use this for a store discount or sale price?+
No. This page is for what is X% of Y, X is what percent of Y, and percentage increase or decrease. For original price, sale price and how much you save, use the Discount Calculator.
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