A percentage calculator online handles the three most common percentage questions in everyday life - covering sales discounts, grade calculations, financial changes, and more.
What is a Percentage?
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 make proportions easy to compare: saying a product is 30% off is more intuitive than saying it costs 70/100 of its original price.
Three Modes Explained
Mode 1: What is X% of Y?
Formula: result = (X / 100) × Y
Example: What is 15% of 200? Result = (15 / 100) × 200 = 30
Use this when: calculating a tip, finding a discount amount, determining a commission.
Mode 2: X is what percent of Y?
Formula: result = (X / Y) × 100
Example: 45 is what percent of 180? Result = (45 / 180) × 100 = 25%
Use this when: calculating a test score percentage, finding what share one number is of a total, measuring performance against a target.
Mode 3: Percentage change from X to Y
Formula: result = ((Y - X) / X) × 100
Example: Sales went from 500 to 650. What is the percentage increase? Result = ((650 - 500) / 500) × 100 = 30% increase
Use this when: measuring revenue growth, tracking price changes, comparing month-over-month metrics.
How to Use the Percentage Calculator
- Open the Percentage Calculator on UtilWave.
- Select the mode that matches your question.
- Enter the known values in the input fields.
- The result appears instantly - no button needed.
- The formula used is shown below the result for reference.
Everyday Percentage Examples
| Scenario | Mode | Example | |---|---|---| | Restaurant tip | Mode 1 | 20% of $45 = $9.00 | | Test score | Mode 2 | 72 is 90% of 80 | | Price increase | Mode 3 | $80 to $96 = 20% increase | | Store discount | Mode 1 | 25% of $120 = $30 off | | Market share | Mode 2 | 15,000 of 60,000 = 25% | | Population growth | Mode 3 | 1,000,000 to 1,150,000 = 15% |
FAQ
What is the formula for percentage decrease? It is the same as percentage change (Mode 3) - if the result is negative, it is a decrease. For example, from 100 to 80: (80-100)/100 × 100 = -20%, meaning a 20% decrease.
Is there a difference between percentage points and percent? Yes. If interest rates go from 3% to 5%, that is an increase of 2 percentage points but a 66.7% increase in the rate itself. The distinction matters in financial and statistical contexts.
Can I calculate compound percentage changes? The percentage change mode calculates a single-step change. For compound changes over multiple periods, use the Compound Interest Calculator.
What is 100% of something? 100% of any value equals that value itself. 100% simply means the whole amount.
Calculate any percentage instantly with the free Percentage Calculator.