How to use Percentage Calculator
The percentage calculator covers three essential percentage operations in one tool: (1) What is X% of Y? (2) X is what percent of Y? (3) What is the percentage change from X to Y? Each panel shows both the answer and the formula used, making it useful for mental-maths checking, grade calculations, discount calculations and financial growth analysis.
- Choose the calculation type using the tab at the top.
- Enter the two numbers for your chosen operation.
- The answer and formula appear instantly.
- Copy the result with the copy button.
Your data never leaves your device — 100% private processing.
Three percentage operations explained
Percent of: (X/100) × Y = result. Useful for calculating tips, discounts and tax. What percent: (X/Y) × 100 = result%. Useful for grade calculations, market share and composition ratios. Percentage change: ((new − old) / old) × 100 = change%. Positive values are increases; negative values are decreases. A drop from 100 to 50 is −50%; a rise from 50 to 100 is +100% — demonstrating that percentage changes are asymmetric.
Percentage points vs percentages
A rise from 10% to 15% is 5 percentage points (absolute difference) but 50% (relative change). Confusing these is extremely common in financial and political reporting. When a central bank raises rates "by 25 basis points" it means 0.25 percentage points (one basis point = 0.01%). When a politician claims "crime fell 50%", verify whether they mean a 50-percentage-point fall or a 50% relative change — the latter is far more common.
| Scenario | Original | New value | Result |
|---|---|---|---|
| 10% of 500 | 500 | — | 50 |
| What % is 45 of 180? | 180 | 45 | 25% |
| Change from 80 to 100 | 80 | 100 | +25% |
| Change from 100 to 80 | 100 | 80 | −20% |
| 15% tip on $60 | $60 | — | $9 |
Worked examples
What is X% of Y?
Inputs: 15% of 80
Result: 12
X is what percent of Y?
Inputs: 45 out of 60
Result: 75%
Percentage change
Inputs: from 80 to 100
Result: +25% increase
Glossary
- Percentage point
- An absolute difference between two percentages; a rise from 10% to 15% is 5 percentage points, not 50%.
- Basis point
- One hundredth of a percentage point (0.01%), used in finance and interest rates.
- Relative change
- A percentage expressing how much a value changed relative to the original value.
- Absolute change
- The raw numerical difference between two values.
Related reading
Frequently Asked Questions
Why use Percentage Calculator?
- Handles all three core percentage operations in a single tabbed interface
- Shows the formula alongside the answer so you understand how each result was reached
- Covers percentage change with correct sign, distinguishing growth from reduction
- Instant copy button for dropping results into spreadsheets or written reports
Common use cases
- Calculate a 20% restaurant tip on a specific pre-tax bill amount
- Find what percentage mark a student scored on a test out of a given total
- Determine the percentage price increase from last year's wholesale cost to this year's
- Work out the final price after a 35% seasonal sale discount is applied
- Compute 8.5% sales tax on a purchase amount when preparing an invoice
Get weekly tool tips & updates
New tools, power-user tips, and productivity hacks — delivered free every Friday.
No spam, ever. Unsubscribe with one click.
Related Calculators
Standard Deviation Calculator
Calculate standard deviation, variance, mean, and sum for a data set. Supports both population and sample formulas. Free and private.
Ratio Calculator
Simplify ratios, scale them up, and solve for a missing value. Great for recipes, mixing, and aspect ratios. Free and private.
Proportion Calculator
Solve proportions for an unknown value. Enter three terms of A/B = C/D and get the fourth, with cross-multiplication shown. Free and private.
BMI Calculator
Calculate your Body Mass Index (BMI) instantly. Supports metric (kg/cm) and imperial (lbs/ft+in) units. Free online BMI calculator.
Discount Calculator
Calculate discounted prices, find what percentage off an item is, or find the original price. Free online discount calculator.
Unit Converter
Convert units of length, weight, temperature, volume, speed, area, and data. A fast, free online unit converter with instant, accurate results.
Explore all Calculators.