Percentage Calculator
A free percentage calculator covers the three calculations people need most: finding a percent of a number, finding what percent one value is of another, and measuring percentage increase or decrease. Switch tabs, enter two values, and see the answer instantly—with green ↑ for increases and red ↓ for decreases on the change tab.
How to Calculate a Percentage
To find X% of Y, convert the percent to a decimal (divide by 100) and multiply: Result = Y × (X ÷ 100). Example: 15% of 80 = 80 × 0.15 = 12. The quick reference table above shows 10%, 15%, 20%, 25%, and 50% of 50, 100, 200, 500, and 1000 for fast lookup.
This basic formula is the foundation of countless everyday calculations: sales tax, tips at restaurants, exam scores, investment returns, and discount shopping. Once you internalize the pattern—divide the percent by 100, then multiply—you can estimate most percentages mentally. For instance, to find 15% of any number, find 10% (move the decimal point one place left) and add half of that result.
How to Calculate Percentage Increase
Percentage increase = ((New − Original) ÷ Original) × 100. If a salary rises from $50,000 to $55,000, the increase is (($55,000 − $50,000) ÷ $50,000) × 100 = 10%. Use Tab 3 with original and new values—the calculator shows a green upward arrow when the new value is higher.
Percentage increase is commonly used to track salary raises, stock price appreciation, population growth, year-over-year revenue improvements, and inflation rates. Understanding this formula helps you evaluate whether a raise or return is meaningful relative to the starting point, rather than just looking at the absolute dollar amount.
How to Calculate Percentage Decrease
The same formula applies; a lower new value yields a negative percentage. Price drops from $200 to $170: ((170 − 200) ÷ 200) × 100 = −15% (a 15% decrease). Tab 3 displays a red downward arrow for decreases—common for discounts and market dips.
An important nuance: a 50% decrease followed by a 50% increase does not return you to the original value. If a $100 item drops 50% to $50, then increases 50%, it only reaches $75—not $100. This asymmetry is why financial analysts track losses and gains carefully, and why recovering from a large percentage drop requires a proportionally larger percentage gain.
The Percentage Formula Explained Simply
% of Y = Y × (X / 100)
X is what % of Y = (X / Y) × 100
% Change = ((New − Original) / Original) × 100
“Percent” literally means “per hundred.” Dividing by 100 converts a percent to a proportion that you can use in multiplication. All three formulas above are just rearrangements of the same core relationship between part, whole, and percentage. Mastering these three variations covers virtually every percentage question you will encounter in school, work, or daily life.
For specialized percentage tasks, try our VAT calculator (adding or removing tax percentages from prices) and tip calculator (splitting a bill with a custom tip percentage).
Real-World Percentage Scenarios
Percentages appear everywhere—from grocery receipts to corporate annual reports. Here are specific contexts where a percentage calculator saves time and prevents errors:
- Shopping discounts — A store advertises 35% off a $120 jacket. Use Tab 1 to find 35% of 120 = $42, so the sale price is $78. During multi-layer sales (e.g., 20% off + additional 10% off), percentages do not simply add—the second discount applies to the already-reduced price.
- Tax calculations — Knowing the sales tax rate in your area lets you estimate the final price before checkout. If tax is 8.25%, use Tab 1 with the item price to calculate the tax amount. For VAT-specific calculations, use our VAT calculator.
- Investment returns — Compare portfolio performance year-over-year using Tab 3. If your portfolio went from $15,000 to $17,250, the gain is 15%. To understand how returns compound over many years, try our compound interest calculator.
- Grade calculations — Scored 42 out of 55 on an exam? Use Tab 2 to find that 42 is 76.36% of 55. This helps students track weighted averages across multiple assignments throughout a semester.
- Nutrition & fitness — Calculate what percentage of your daily calories comes from protein, carbs, or fat. If you consumed 2,200 calories and 650 came from protein, Tab 2 shows protein is 29.5% of your intake.
These examples demonstrate why mastering three simple percentage formulas gives you a versatile tool for everyday decision-making—from budgeting and shopping to fitness tracking and academic performance.
Frequently Asked Questions
How do I calculate 20% of a number?
Multiply the number by 20 and divide by 100—or simply multiply by 0.20. Example: 20% of 150 = 150 × 0.20 = 30. Use Tab 1 on this page: enter 20 and 150 to get the result instantly. A quick mental-math shortcut for 20% is to find 10% (move the decimal one place left) and then double it. So 10% of 150 is 15, and doubling gives you 30. This trick works for any multiple of 10%.
How do I find what percentage one number is of another?
Divide the part by the whole, then multiply by 100. Example: 45 is what percent of 180? (45 ÷ 180) × 100 = 25%. Use Tab 2: enter 45 as the part and 180 as the whole. This calculation is useful in many real-world situations: determining what percentage of a budget has been spent, what share of students passed an exam, or what fraction of a target has been reached. The formula is always: (Part ÷ Whole) × 100 = Percentage.
What is percentage change and how do I calculate it?
Percentage change measures growth or decline from an original value to a new value using the formula: ((New − Original) ÷ Original) × 100. A positive result indicates an increase; a negative result indicates a decrease. Tab 3 computes this and shows a green upward arrow for increases and a red downward arrow for decreases. This is the most common formula used in finance, economics, and business reporting to express how much something has grown or shrunk over time.
How do I calculate a discount percentage?
If an item was $80 and is now $60, the change is −25% (a 25% discount). Enter original 80 and new 60 in Tab 3. To find the sale price after a known discount, use Tab 1 with the discount percentage and the original price, then subtract the result from the original. For example, 25% of $80 = $20, so the sale price is $80 − $20 = $60. Alternatively, multiply the original price by (1 − discount/100): $80 × 0.75 = $60.
What is the difference between percentage points and percentages?
A percentage point is an absolute difference between two percentages, while a percentage is a relative measure. If an interest rate rises from 3% to 5%, that is a 2 percentage point increase but a 66.7% increase in relative terms ((5−3)/3 × 100). This distinction matters in finance, statistics, and news reporting. When someone says "unemployment rose by 2 percent," they often mean 2 percentage points, but the mathematical meaning is very different.
Can percentages be greater than 100%?
Yes. A percentage over 100% simply means the value exceeds the reference amount. For example, if your company's revenue grew from $50,000 to $120,000, the percentage increase is 140%. If you scored 55 out of 50 on an extra-credit exam, that is 110%. Values above 100% are common when measuring growth, profit margins, and efficiency improvements. Tab 3 on this calculator handles values over 100% correctly.
Disclaimer: Results are for educational and general reference purposes only. Always double-check critical financial, tax, or academic calculations with the relevant authority.