This calculator handles three of the most common percentage problems. Select the calculation type that matches your question, enter your two values, and get an instant result.
What is X% of Y? — Multiplies Y by X divided by 100. Use this to find a percentage of any number, such as a tip amount, a discount, or a tax figure.
X is what % of Y? — Divides X by Y and multiplies by 100. Use this when you want to express one number as a proportion of another, such as a test score or a budget allocation.
Percentage Increase/Decrease — Subtracts the original value from the new value, divides by the original, and multiplies by 100. A positive result means an increase; a negative result means a decrease.
You're leaving a tip at a restaurant. The bill is $85 and you want to leave 20%. Enter 20 as Value 1 and 85 as Value 2 under "What is X% of Y?" — the result is $17.00. Your total including tip would be $102.
You scored 43 out of 55 on a test and want to know your percentage grade. Enter 43 as Value 1 and 55 as Value 2 under "X is what % of Y?" — the result is 78.18%.
A product cost $120 last month and now costs $95. Enter 120 as Value 1 and 95 as Value 2 under "Percentage Increase/Decrease" — the result is −20.83%, meaning the price dropped by about 21%.
Multiply the number by the percentage divided by 100. For example, 20% of 50 is calculated as 50 × (20 ÷ 100) = 50 × 0.20 = 10. This is the most common percentage calculation and is useful for tips, discounts, taxes, and commissions.
Subtract the original value from the new value, divide the result by the original value, then multiply by 100. For example, if a salary goes from $50,000 to $55,000, the increase is ($55,000 − $50,000) ÷ $50,000 × 100 = 10%. Use the "Percentage Increase/Decrease" mode in this calculator to do this instantly.
Percentage decrease uses the same formula as percentage increase. If the result is negative, the value went down. For example, if a stock drops from $200 to $170, the change is ($170 − $200) ÷ $200 × 100 = −15%, a 15% decrease.
These are often confused. If an interest rate rises from 3% to 5%, it increased by 2 percentage points, but it increased by 66.7% in relative terms (2 ÷ 3 × 100). Percentage points describe absolute change between two percentages; percentage change describes relative change. This calculator computes relative percentage change.
If you know the final price after a discount and want the original price, divide the final price by (1 − discount rate). For example, if an item costs $80 after a 20% discount, the original price was $80 ÷ 0.80 = $100. This is a reverse percentage calculation that isn't directly in this tool but is straightforward to do manually.
Percentages appear constantly in finance and daily decisions: interest rates on loans and savings accounts, sales tax, tips at restaurants, discounts and markups in retail, nutritional information on food labels, test and exam scores, investment returns, and statistics in news and research. Understanding how to quickly calculate percentages is one of the most broadly useful math skills in everyday life.