Online Percentage Calculator
Calculate percentages, growth rates, discounts, and numerical changes. Supports six calculation modes with real-time results and step-by-step formulas.
What is Y% of X?
X × Y ÷ 100Calculation Examples
| Question | Method | Result |
|---|---|---|
| What is 20% of 500? | 500 × 20% | 100 |
| 50 is what % of 200? | 50 ÷ 200 × 100% | 25% |
| 80 increased to 100 | (100−80)÷80×100% | +25% |
| 500 decreased by 15% | 500×(1−15%) | 425 |
| 80 after 20% off, original? | 80÷(1−20%) | 100 |
| 500 with 12% discount | 500×(1−12%) | 440 |
About This Tool
This percentage calculator supports six common percentage scenarios: finding a percentage of a number, calculating what percent one number is of another, measuring percentage change, applying increases or decreases, reverse-calculating original values, and computing discounts. All calculations run locally in your browser and are not uploaded to any server.
How to Use
- 1Select a calculation mode from the tabs at the top.
- 2Enter the required values in the input fields.
- 3Results are calculated in real time as you type.
- 4Adjust decimal places using the precision selector.
- 5Click Copy Result to copy the output, or Load Example to try a sample.
Calculation Rules
Percentage Change vs Percentage Difference
Percentage change has a clear direction: an old value and a new value. It is calculated as (new − old) ÷ |old| × 100%. Percentage difference, on the other hand, compares two values without a before/after relationship, using |A − B| ÷ ((|A| + |B|) ÷ 2) × 100%. The two formulas and results are different.
Profit Margin vs Markup
Profit margin = profit ÷ selling price × 100%. Markup = profit ÷ cost × 100%. For example, with a cost of 80 and selling price of 100: profit margin is 20%, markup is 25%. These two concepts are often confused.
Limitations
- ⚠This tool provides general calculations only and does not constitute tax or financial advice.
- ⚠Percentage change cannot be calculated when the original value is zero.
- ⚠Discount percentages above 100% are not valid for standard pricing.
- ⚠Results are rounded to the selected decimal precision.
- ⚠100 increased by 20% becomes 120, then decreased by 20% becomes 96 — not 100, because the base changes.
Frequently Asked Questions
▶What is the difference between percent and percentage point?
A percentage point is the absolute difference between two percentages. For example, going from 20% to 25% is a 5 percentage point increase, but a 25% relative increase.
▶If something increases 20% then decreases 20%, why doesn't it return to the original?
Because the base changes. 100 + 20% = 120. 120 − 20% = 96. The 20% decrease is applied to 120, not 100.
▶What does '20% off' (eight-tenths) mean?
20% off means you pay 80% of the original price. In Chinese, '八折' (eight-tenths) means paying 80%, which is a 20% discount.
▶Can I calculate growth rate when the original value is 0?
No. Percentage change requires a non-zero original value because division by zero is undefined.
▶Why do some results have many decimal places?
Some divisions produce repeating decimals. Use the decimal precision selector to round to 0, 2, or 4 places.
▶How is discount different from percentage decrease?
They use the same formula. A 20% discount is the same as decreasing by 20%. The discount mode just adds 'you save' information.
Related Tools
Related Articles
- 📄How to calculate percentage change correctly
- 📄Difference between profit margin and markup
- 📄How to calculate discount and final price
- 📄Why increasing then decreasing by the same percent doesn't return to original
- 📄Understanding percentage points vs percent