Web Tools
Percent Calculator
Calculate percentages with 4 modes: what is X% of Y, what percent is X of Y, percentage change from A to B, and find value from percentage and result. Shows formulas and supports configurable precision. Runs entirely in your browser — your data never leaves your machine.
percent percentage calculator math change ratio
Published May 30, 2026
All interactive tools run entirely in your browser. Your data never leaves your device.
How It Works
Choose a calculation mode and enter two values. The calculator instantly shows the result, the formula used, and a formatted human-readable answer. Adjust decimal precision from 0 to 10 places.
Features
- X% of Y: calculate a percentage of a value (e.g., 20% of 150 = 30)
- X is ?% of Y: find what percentage one number is of another
- % Change: calculate percentage increase or decrease between two values
- Find Value: reverse-calculate the total when you know the percentage and result
- Formula display: see the exact mathematical formula used
- Configurable precision: 0–10 decimal places
- Direction indicator: shows increase, decrease, or no change for % change mode
- 6 examples: tips, discounts, ratios, price changes
- Private: runs entirely in the browser — no data transmitted
Use Cases
- Calculating tips, discounts, and tax amounts
- Finding percentage changes in metrics and KPIs
- Determining what fraction one number is of another
- Reverse-calculating totals from known percentages
- Quick math for financial calculations