Percentage Calculator
🔒 Local only Education & Statistics Tools
Find a percentage of a number, ratios, and percentage change.
This percentage calculator covers three common needs: a percentage of a number (what is X% of Y), a ratio (X is what percent of Y), and percentage change (how much did A change to B). Results update as you type and everything runs locally in your browser — handy for discounts, grade weighting, and data analysis.
Tool area
How to use
- Pick the calculation you need: percentage, ratio, or change.
- Enter the numbers in the matching fields.
- Results show instantly — no calculate button needed.
- Adjust the numbers anytime to see updated results.
Use cases
- Work out how much a discount saves you (for example 25% off).
- Find what percent a score is of the total.
- Calculate growth from one period to the next.
FAQ
- How is "X% of Y" calculated?
- It equals Y × X ÷ 100. For example, 25% of 200 is 50.
- Which value is the base for percentage change?
- The original value (A) is the base: (B − A) ÷ A × 100. Positive means an increase, negative a decrease.
- Can I calculate change when the original is 0?
- No. Percentage change is undefined when the original value is 0, and the tool will flag it.
- Can I enter decimals?
- Yes, all three calculations support decimal input.
- Is my data uploaded?
- No, all calculations run locally in your browser.
Privacy & local processing
🔒 This tool runs entirely in your browser. No data is uploaded to any server.
All calculations run locally in your browser; the numbers you enter are not uploaded.
Trust & usage note
This tool runs mainly in your browser. Your input is not actively uploaded to a server. Avoid entering highly sensitive data. Results are for reference only.
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