Percentage Calculator - Calculate Percent Instantly
Three calculation modes: find a percentage of a number, determine what percent one number is of another, or calculate percentage change.
What Is a Percentage Calculator?
A percentage calculator solves the three most common percentage problems: finding what X% of a number is, determining what percentage one number is of another, and calculating the percentage change between two values. It's used daily by students, shoppers calculating discounts, analysts comparing data, and anyone working with proportions.
How to Calculate Percentages
- Choose a Mode — Select one of three tabs: "X% of Y", "X is ?% of Y", or "% Change"
- Enter Values — Type your numbers into the input fields
- See Result — The answer appears instantly with the full formula shown below
- Copy or Review — Click the result to copy it, or scroll down to see your calculation history
Why Use This Percentage Calculator?
- Three Modes — Covers all common percentage calculations in one tool
- Shows Formula — See the full calculation formula, not just the answer
- History — Keeps a log of your recent calculations for easy reference
- Real-Time — Results update instantly as you type, no button needed
- Copy Result — Click the result box to copy the full expression to clipboard
- Privacy — Everything runs in your browser, no data sent anywhere
FreeToolbox vs Other Percentage Calculators
| Feature | FreeToolbox | Calculator.net | Omni Calculator |
|---|---|---|---|
| Modes | 3 | 3 | 1 per page |
| Real-time | Yes | No (button) | Yes |
| History | Yes | No | No |
| Shows Formula | Yes | Yes | Yes |
| Ads | Minimal | Heavy | Heavy |
| Privacy | Browser-only | Server | Server |
FAQ
How do I calculate X% of a number?
Use the first mode (X% of Y). For example, to find 15% of 200, enter 15 and 200. The answer is 30.
How do I find what percentage one number is of another?
Use the second mode (X is ?% of Y). For example, to find what percent 30 is of 200, enter 30 and 200. The answer is 15%.
How is percentage change calculated?
Percentage change = ((New Value - Old Value) / |Old Value|) × 100. A positive result means an increase, negative means a decrease.
Is there a limit on the numbers I can enter?
No practical limit. The calculator handles any number your browser can process, including decimals.
Is my calculation history saved?
History is saved in your browser's local storage. It persists between visits but never leaves your device. Click 'Clear' to delete it anytime.