📊 Percentage Calculator — Instant, Accurate & Private

Calculate percentages, percentage change, percentage increase, percentage decrease, fractional to percent conversions, and more — instantly in your browser. This tool runs entirely locally so your numbers never leave your device.

💡 How Percentages Work — Quick Reference

Percentages express numbers as parts of 100. Use percentages to calculate discounts, tax, commission, grade scores, profit margins, interest rates, and data comparisons. This calculator supports common percentage tasks: converting fractions to percent, calculating X% of Y, finding what percent X is of Y, calculating percentage increase/decrease, and determining percentage change between two values.

⚙️ Common Formulas

• Finding X% of Y: (X ÷ 100) × Y
• Finding what % X is of Y: (X ÷ Y) × 100
• Percentage Change: ((New − Original) ÷ Original) × 100
• Increase by P%: Original × (1 + P/100)
• Decrease by P%: Original × (1 − P/100)

🔒 Privacy & Accuracy

All calculations are performed locally in your browser using JavaScript — nothing is transmitted to external servers. Results are rounded to two decimal places for readability; re-check critical financial calculations with your accounting tools.

📚 Learn More — Trusted External Resources

• Read percentage basics on Wikipedia — Percentage.
• Brush up math fundamentals at Khan Academy — Percent.
• See business examples and financial context at Investopedia — Percentage.

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❓ Frequently Asked Questions

How do I calculate X% of Y?

Multiply Y by X/100. Example: 20% of 500 = 500 × (20/100) = 100.

How do I find what percent X is of Y?

Divide X by Y, then multiply by 100. Example: X=45, Y=60 → (45/60)×100 = 75%.

How is percentage change calculated?

(New − Original) ÷ Original × 100. Positive = increase; negative = decrease.

Is this calculator secure?

Yes — all calculations run locally in your browser using JavaScript. No values are sent to external servers.

Can I use this for financial calculations?

This tool provides quick estimates and rounding to two decimal places. For legal, tax, or high-precision financial work, verify results with professional accounting software or a certified accountant.