Percentage Calculator
Find percentages, compare values, calculate increases or decreases, and work backwards from a final amount—quickly and accurately.
Calculate Percentages Instantly
Choose a method, enter your numbers, and see the formula with your result.
Your Percentage Result
✓ Calculated20% of 150 equals 30.
150 × (20 ÷ 100) = 30
How to use the Percentage Calculator
Choose the type of percentage question you have. The calculator shows the answer, supporting values and the exact formula so you can understand each step.
Pick percentage of, what percent, percentage change, increase/decrease or reverse percentage.
Type the percentage and numbers. Choose increase or decrease when needed.
Select Calculate → to see the result, additional values and working formula.
Percentage formulas with examples
These five calculations cover everyday questions about discounts, test scores, sales, budgets, price changes and financial comparisons.
(20 ÷ 100) × 150 = 30Convert the percentage to a decimal and multiply by the original amount.
(30 ÷ 150) × 100 = 20%Divide the part by the whole, then multiply by 100.
((150 − 120) ÷ 120) × 100 = 25%A positive result means an increase; a negative result means a decrease.
200 × (1 + 15 ÷ 100) = 230For decreases, replace the plus sign with minus.
230 ÷ (1 + 15 ÷ 100) = 200Reverse percentages are useful for working backwards from a final price or amount.
The percentage-change tool uses the absolute magnitude of the original value as its denominator when the original is negative. A percentage change from zero is undefined, so the calculator flags that case rather than showing an incorrect answer.
When is a percentage calculator useful?
Use percentage calculations to find sale discounts, tax amounts, exam scores, tips, growth rates and budget changes. The percentage change is not the same as the difference in percentage points. For example, a rate moving from 10% to 15% increases by 5 percentage points, but its relative percentage increase is 50%.
In a discount calculation, 20% off a price of 150 means the reduction is 30, so the final price is 120. Choose Percent of to find the discount amount or Increase / Decrease to find the final price directly.
Frequently Asked Questions
How do I calculate a percentage of a number?
Divide the percent by 100 and multiply by the number. For example, 15% of 200 is (15 ÷ 100) × 200 = 30.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. For instance, 30 out of 150 is 20%.
How do I calculate percentage increase?
Subtract the starting number from the new number, divide by the absolute value of the starting number, then multiply by 100. A result above zero indicates an increase.
How do I calculate percentage decrease?
Use the percentage-change formula: (new − original) ÷ |original| × 100. For positive starting values, a negative answer represents a percentage decrease.
How can I add 20% to a number?
Multiply the number by 1.20, or select Increase / Decrease, enter 20%, and choose Increase.
How can I find an original price before a percentage increase?
Use Reverse %, enter the final price and the increase percent, and choose Increased by %. The calculator divides the final price by (1 + percentage ÷ 100).
Why is percentage change from zero undefined?
Relative percentage change requires division by the starting value. Division by zero is undefined, so a zero original value cannot produce a finite percentage change.
Can percentages be more than 100% or negative?
Yes. A percentage of a number can be over 100% or negative. For increase, decrease and reverse calculations, enter a nonnegative adjustment rate and select the direction separately.