Percentage Calculator
Calculate percentages, ratios, and percent change in real time.
Three modes for every everyday calculation need.
About
The Percentage Calculator is a free tool that handles three everyday percentage calculations in real time. Whether you need to find a percentage of a number, determine what percent one number is of another, or calculate percentage change, just type in the values and the result appears instantly.
From discount shopping and tax calculations to growth analysis and grade scoring, percentages come up everywhere. This tool makes those calculations fast and accurate without any mental arithmetic.
All calculations run locally in your browser. No input data is sent to any server.
How to Use
Choose a Mode
Select one of the three tabs. You can also link directly to a mode using #mode1, #mode2, or #mode3 in the URL.
Enter Numbers
Type values into the two input fields. Results appear in real time as you type — no need to press any button.
Read the Result
The result is shown in large text. Increases appear in green, decreases in red, for quick at-a-glance reading.
Glossary
- Percentage (%)
- A ratio expressed as a fraction of 100. The word comes from the Latin "per centum," meaning "by the hundred."
- Per Mille (‰)
- A ratio per thousand. 1% equals 10‰. Used in finance (interest rates) and statistics.
- Percentage Point (pp)
- The arithmetic difference between two percentages. A rise from 10% to 15% is 5 pp, not a 50% increase.
- Percentage Change
- How much a value has increased or decreased relative to its original. Formula: (New − Old) ÷ Old × 100.
- Ratio
- The relative size of two quantities. A ratio of 3:2 equals 60% to 40%.
- Discount Rate
- The percentage reduction from the original price. A 20% discount means paying 80% of the listed price.
- Base Value
- The reference value against which a percentage is calculated (the denominator). Changing the base changes the result entirely.
- Compound Percentage
- Applying a percentage to a value that has already been changed by another percentage (e.g., two successive discounts).
FAQ
- Q.What is a percentage?
- A percentage is a way of expressing a number as a fraction of 100. For example, 50% means half of a whole.
- Q.How do I calculate 25% of 100?
- 100 × 25 ÷ 100 = 25. Enter the values in Mode 1 for instant results.
- Q.How is percentage change calculated?
- (New value − Old value) ÷ Old value × 100. Example: from 80 to 100 is a 25% increase.
- Q.Can I use it for discount calculations?
- Yes. Enter the original price and discount rate in Mode 1 to find the discount amount.
- Q.Is my data sent to a server?
- No. All calculations are performed locally in your browser. No data is sent externally.
- Q.Can I calculate with decimals?
- Yes. Both inputs and results support decimal numbers.
- Q.What is the difference between per mille and percent?
- Percent (%) is per hundred, per mille (‰) is per thousand. 1% = 10‰.
- Q.Can I calculate sales tax?
- Yes. Enter the pre-tax price and tax rate in Mode 1 to find the tax amount.
Use Cases
Shopping Discounts
Instantly calculate sale prices and final amounts. Great for comparing deals on the spot.
Business Growth Analysis
Calculate month-over-month or year-over-year growth rates for quick reports.
Test Score Percentages
Convert correct answers and total questions into a percentage score.
Tax & Tip Calculations
Find the tax or tip amount from any price and rate — useful at home and when traveling.