Percentage Calculator
Calculate percentages instantly in four different modes — all processing happens in your browser.
History
How to Use the Percentage Calculator
Select the mode that matches your calculation, enter the numbers, and see the result instantly. No button press needed — results update as you type.
- Choose a mode using the tabs: "X% of Y", "X is ?% of Y", "% Change", or "% Difference".
- Enter the values in the input fields. Decimals and negative numbers are supported.
- Read the result on the right (or below on mobile). The formula used is shown underneath.
- Copy the result to your clipboard using the Copy button, or share it directly.
Percentage Formulas
Every percentage calculation is based on one of these four formulas:
X% of Y:
Result = (X / 100) × Y
X is what % of Y:
Percentage = (X / Y) × 100
Percentage Change:
Change = ((New - Old) / |Old|) × 100
Percentage Difference:
Difference = (|A - B| / ((A + B) / 2)) × 100
Common Percentage Examples
| Question | Formula | Answer |
|---|---|---|
| What is 15% of 200? | (15/100) × 200 | 30 |
| What is 20% of 150? | (20/100) × 150 | 30 |
| 50 is what % of 250? | (50/250) × 100 | 20% |
| % change from 80 to 100 | ((100-80)/80) × 100 | 25% increase |
| % difference between 40 and 60 | (20/50) × 100 | 40% |
Guide to Percentages
A percentage is a way of expressing a number as a fraction of 100. The word comes from the Latin per centum, meaning "by the hundred." Percentages are everywhere in everyday life — from discounts in shops to interest rates on loans, tax rates, and academic grades.
Understanding the difference between percentage change and percentage difference is important. Percentage change compares a new value to an original value and tells you whether something increased or decreased. Percentage difference compares two values without implying that one is the starting point, which is useful when neither value is the "original."
When working with percentages, always pay attention to the base value (the number you are taking a percentage of). A 50% increase followed by a 50% decrease does not bring you back to the original number — it leaves you at 75% of where you started. This is a common mistake in financial reasoning.
Percentages can exceed 100%. A 200% increase means the new value is three times the original. Percentages can also be negative — a -10% change means a 10% decrease.