Percentage
calculator.
Work out percentages, find an original value, compare changes and see exactly how each result is calculated.
15% of 200 equals 30.
(15 / 100) × 200 = 30The math
made simple.
How do you calculate a percentage?
Divide the percentage by 100, then multiply it by your base value. To find 15% of 200, calculate (15 ÷ 100) × 200. The result is 30.
What's the difference between percent change and percentage points?
Suppose a survey result increases from 4% to 6%. That's a rise of 2 percentage points. Relative to the original 4%, the increase is 50%. The two answers describe the same change in different ways.
How do you reverse a percentage change?
If an item costs $80 after a 20% discount, divide 80 by 0.8 to recover the original price of $100. A full 100% decrease can't be reversed because every starting amount becomes zero.
What happens when the starting value is negative?
Percentage change here uses the absolute starting value in the denominator. Moving from −50 to −25 is a positive 50% change under that convention. Other fields can define change differently, so check the displayed formula when comparing results.
How precise are the results?
Calculations run locally in your browser using JavaScript number arithmetic. Answers are rounded for display when needed. A zero denominator, an undefined reverse calculation, or a result outside the supported numeric range produces an explicit error.
Method: standard arithmetic definitions. Calculation formulas are shown alongside your results; no external data feeds are used.