Percentage Calculator
Three percentage calculators in one. Find a percentage of a number, calculate percentage increase or decrease between two values, or determine what percentage one number is of another.
Percentage Of
What is X% of Y?
Percentage Change
What is the percentage increase or decrease from X to Y?
What Percent?
X is what percentage of Y?
How to use
This page includes three separate percentage calculations. Use "Percentage Of" to find a specific percentage of any number (e.g., what is 15% of 200?). Use "Percentage Change" to find the increase or decrease between an old and new value. Use "What Percent?" to determine what percentage one number is of another.
Formulas
When this calculator helps
Percentage calculations come up everywhere, calculating tips, understanding discounts, tracking investment returns, analyzing test scores, and computing tax rates. While the math is straightforward, it is easy to make errors, especially with percentage change and reverse percentage problems. Students use this calculator for homework and exam prep. Business professionals use it for financial analysis, pricing decisions, and reporting. Shoppers use it to verify sale prices and compare deals. Having three calculation modes in one tool covers virtually every percentage scenario you will encounter.
Examples
Example 1: Shopping Discount
A jacket originally priced at $89.99 is 35% off. Using the "Percentage Of" calculator: 35% of $89.99 = $31.50 discount. The sale price is $89.99 - $31.50 = $58.49. If there is an additional 10% off at checkout, that saves another $5.85, bringing the final price to $52.64, a total of 41.5% off.
Example 2: Year-Over-Year Revenue Growth
A business earned $450,000 last year and $520,000 this year. Using "Percentage Change": ($520,000 - $450,000) / $450,000 × 100 = 15.6% growth. If the industry average growth is 8-10%, this company is outperforming. Investors and stakeholders care deeply about this metric.
Example 3: Test Score Analysis
A student scored 42 out of 55 on an exam. Using "What Percent": 42 / 55 × 100 = 76.4%. If the passing grade is 70%, they passed with a 6.4 percentage point margin. To reach an 85% (46.75 points), they would need roughly 5 more correct answers next time.
Things to watch
- •A 50% increase followed by a 50% decrease does not return to the original, $100 + 50% = $150, then $150 - 50% = $75 (a net 25% loss).
- •When stacking multiple discounts (e.g., 20% off then 10% off), the total discount is 28%, not 30%, multiply the remaining percentages.
- •Always check which number is the base when calculating percentages, "A is 50% more than B" is different from "B is 33% less than A."
- •For percentage change, the order matters: going from 80 to 100 is a 25% increase, but going from 100 to 80 is a 20% decrease.
- •Convert percentages to decimals (divide by 100) before multiplying in multi-step calculations to avoid errors.
Sources and methodology
Last reviewed: Checked during calculator QA. We review formulas, default assumptions, and examples against public references when a formal source applies.
Method: This calculator uses the formula explained on this page. We also check example results by hand to catch obvious mistakes.
Found something off? Send a correction with the page URL, inputs, result, and expected result.
Common questions
- How do I calculate a percentage of a number?
- To find X% of a number, multiply the number by X and divide by 100. For example, 15% of 200 is 200 × 15 ÷ 100 = 30. You can also convert the percentage to a decimal first: 15% = 0.15, then 200 × 0.15 = 30.
- How do I calculate percentage increase or decrease?
- Subtract the old value from the new value, divide by the old value, and multiply by 100. If something went from $80 to $100, the increase is (100 - 80) / 80 × 100 = 25%. For a decrease, the result will be negative.
- How do I reverse a percentage to find the original number?
- If you know the result after a percentage increase, divide by (1 + percentage/100). For example, if a price is $120 after a 20% increase, the original was $120 / 1.20 = $100. For a decrease, divide by (1 - percentage/100). A $80 price after 20% off means the original was $80 / 0.80 = $100.
- What is the difference between percentage points and percent?
- Percentage points measure the absolute difference between two percentages. Percent measures relative change. If an interest rate goes from 5% to 7%, that is a 2 percentage point increase but a 40% relative increase (2/5 × 100). This distinction matters in finance, statistics, and news reporting.
- How do I calculate a percentage of a percentage?
- Multiply the two percentages as decimals. For example, 30% of 50% is 0.30 × 0.50 = 0.15 = 15%. A common use case: if 60% of customers visit your site on mobile, and 25% of mobile visitors make a purchase, then 15% of all visitors buy on mobile.