Percentage Calculator
Solve everyday percentage problems: X% of Y, what % is X of Y, percent change (increase/decrease), find the original before a percentage change. Live results, history, and shareable deep-links.
About this tool
Percentages are everywhere — discounts, taxes, tips, interest rates, salary increases, exam scores. This calculator solves the four most common percentage problems and shows the step-by-step working so you can verify the result.
X% of Y — e.g. what is 15% of 200? Answer: 30. Useful for calculating a discount or tip.
X is what % of Y — e.g. 30 is what percent of 200? Answer: 15%. Useful for working out a test score or market share.
% change — e.g. the change from 200 to 250 is a 25% increase. Useful for price changes or growth rates.
Find original — e.g. the price after a 15% increase is 230, so the original was 200. Useful for reversing a tax or markup.
Each result includes a breakdown of the arithmetic so you can follow along, and your recent calculations are saved locally for quick reference.
FAQ
How is percentage change calculated? ›
Subtract the original from the new value, divide by the absolute value of the original, then multiply by 100. A positive result is an increase; a negative result is a decrease. The tool labels the direction automatically.
Why is the "Find Original" mode useful? ›
If you know a price after tax (e.g. €230 including 15% VAT) and want the pre-tax amount, divide 230 by 1.15 to get 200. The tool handles this calculation — including decreases — and shows the steps.
Can I use decimals and negative numbers? ›
Yes. The inputs accept any numeric value including decimals and negatives. Percent change from −50 to −30 is correctly handled, as is "X is what % of Y" with negative totals.
Are my calculations saved? ›
Recent results are stored in your browser's localStorage so you can refer back to them. They never leave your device. Use the "Clear" button to wipe the history at any time.