Percentage Calculator
Calculate percentages, percent change, and more
Last updated: January 2025
About This Tool
A percentage calculator is an essential tool for computing percentages in everyday situations - from calculating discounts and taxes to understanding growth rates and comparing proportions. Mastering percentages helps with financial decisions and data analysis.
What is Percentage Calculator?
A percentage is a way of expressing a number as a fraction of 100, using the percent symbol (%). Percentages are used universally to express proportions, changes, and comparisons. A percentage calculator performs various percentage-related calculations including finding what percentage one number is of another, calculating percent change, and applying percentage increases or decreases.
How It Works
The calculator uses different formulas depending on the calculation type. To find X% of Y, multiply Y by X/100. To find what percent X is of Y, divide X by Y and multiply by 100. For percent change, subtract the old value from the new value, divide by the old value, and multiply by 100.
Formula
X% of Y = (X / 100) x Y | Percent Change = ((New - Old) / Old) x 100
What is X% of Y?
Result
50.00
25% of 200 = 50.00
Common Percentages
Percentage Formulas
X% of Y
(X / 100) × Y
X is what % of Y
(X / Y) × 100
Percent Change
((New - Old) / Old) × 100
Increase by X%
Value × (1 + X/100)
Related Tools
When to Use This Calculator
- 1Calculating discounts and sale prices while shopping
- 2Determining tax amounts on purchases
- 3Computing percentage grades in academics
- 4Analyzing growth rates in business and investments
- 5Comparing proportions and market shares
Pro Tips
- •Move decimal two places left to convert percentage to decimal (25% = 0.25)
- •To find 10% quickly, just move the decimal one place left
- •For 15%, calculate 10% and add half of that amount
- •Remember: percentage increase is not the same as percentage points
- •Always identify the "whole" (base) when calculating percentages
Common Mistakes to Avoid
- •Confusing percentage points with percent change
- •Calculating percent change with wrong base (new vs old)
- •Adding percentages directly instead of calculating on the base
- •Forgetting that 50% increase followed by 50% decrease is not zero change
- •Mixing up markup percentage with profit margin