Everyday Calculators
Percentage Calculator
Calculate percentages, percentage increase, percentage decrease, percentage change, and percentage difference with formulas and examples.
Enter the values and review the result.
Calculate percentage
Choose a percentage calculation, enter your values, and see the formula with a step-by-step answer.
Choose a percentage calculation and enter your values.
The result will show the answer, formula, substitution, and short explanation.
Which percentage calculation should you use?
Percent of a number
Use this for questions like: what is 20% of 150?
What percent?
Use this when you know the part and whole, like 30 of 200.
Percentage increase
Use this when a value goes up, like 50 increasing to 55.
Percentage decrease
Use this when a value goes down, like 80 decreasing to 60.
Percentage change
Use this for before-and-after comparisons, like 40 to 50.
Percentage difference
Use this when comparing two values without a clear old value.
How to find percentage of a number
To find X% of a number, convert the percentage to a decimal and multiply by the number.
X% of Y = X / 100 × Y
20% of 150 = 20 / 100 × 150 = 30
How to calculate percentage increase
Percentage increase compares how much a value went up compared with the original value.
Percentage increase = (new value - original value) / original value × 100
100 to 125: (125 - 100) / 100 × 100 = 25%
How to calculate percentage decrease
Percentage decrease compares how much a value went down compared with the original value.
Percentage decrease = (original value - new value) / original value × 100
200 to 150: (200 - 150) / 200 × 100 = 25%
How to find the original value
Reverse percentage problems start with the final value and work backward. Use this when you know a sale price after a discount or a new value after an increase.
Original before increase = new value / (1 + percentage / 100)
Original before decrease = sale value / (1 - percentage / 100)
$75 after 25% off: 75 / (1 - 25 / 100) = $100
Percentage change vs percentage difference
Percentage change compares an old value to a new value. Percentage difference compares two values using their average as the reference. Use percentage change for before/after changes, and use percentage difference when there is no clear original value.
Percentage change from 80 to 100: (100 - 80) / 80 × 100 = 25%
Percentage difference between 40 and 50: |50 - 40| / ((40 + 50) / 2) × 100 = 22.22%
Common percentage formulas
| Calculation | Formula | Example |
|---|---|---|
| X% of Y | X / 100 × Y | 20% of 150 = 30 |
| X is what percent of Y | X / Y × 100 | 30 of 150 = 20% |
| Percentage increase | (new value - original value) / original value × 100 | 100 to 125 = 25% |
| Percentage decrease | (original value - new value) / original value × 100 | 200 to 150 = 25% |
| Percentage change | (new value - old value) / old value × 100 | 80 to 100 = 25% |
| Percentage difference | |A - B| / ((A + B) / 2) × 100 | 40 and 50 = 22.22% |
| Original value before increase | new value / (1 + percentage / 100) | 125 after 25% increase = 100 |
| Original value before decrease | sale value / (1 - percentage / 100) | $75 after 25% off = $100 |
Worked examples
What is 20% of 150? 20 / 100 x 150 = 30.
50 increased by 10%: 50 + (50 x 0.10) = 55.
80 decreased by 25%: 80 - (80 x 0.25) = 60.
What percent is 30 of 200? 30 / 200 x 100 = 15%.
Percentage change from 40 to 50: (50 - 40) / 40 x 100 = 25%.
15% of 80: 15 / 100 × 80 = 12.
25 is what percent of 200: 25 / 200 × 100 = 12.5%.
Increase from 50 to 75: (75 - 50) / 50 × 100 = 50%.
Decrease from 120 to 90: (120 - 90) / 120 × 100 = 25%.
Percentage change from 80 to 100: (100 - 80) / 80 × 100 = 25%.
Percentage difference between 40 and 50: |40 - 50| / ((40 + 50) / 2) × 100 = 22.22%.
Original price before a 25% discount: 75 / (1 - 25 / 100) = 100.
Common mistakes
- Dividing by the wrong original value.
- Confusing percentage change with percentage difference.
- Forgetting to multiply by 100.
- Using the new value instead of the original value as the base.
- Treating percentage points and percentages as the same thing.
- Comparing percentages without checking the base values behind them.
- Rounding too early before the final answer.
Real-life uses
Percentage calculations help with discounts and sales, taxes and tips, price increases, grade percentages, finance and interest, business growth, and comparing two values.
For related tasks, try the Discount Calculator, Sales Tax Calculator, Tip Calculator, Percentage Increase Calculator, Percentage Decrease Calculator, and Percentage Change Calculator.
For business and finance examples, compare percent changes with the Profit Margin Calculator, ROI Calculator, or Scientific Calculator.
You can also read the Percentage Calculator Guide and Understanding Percentages, browse Everyday Calculators, explore Math Calculators, or review Business Calculators.
Quick answers
What this calculator answers
- Result: Calculates percent of, percent as part of a whole, increase, decrease, change, and percentage difference.
- Formula: Shows the exact formula and substitution so you can check the math.
- Use cases: Useful for discounts, taxes, tips, grades, price changes, growth, and comparing two values.
- Limit: Use the original or old value as the base for percentage change calculations.
- Related guide: Review practical percentage formulas and common mistakes. percentage calculator guide
Transparency note
Accuracy and limitations
Calzivo tools are built for practical estimates, conversions, and checks. Some tools use standard formulas or simplified assumptions, and results can be affected by input accuracy, rounding, units, local rules, or changing official requirements.
Results depend on the values you enter and any simplified assumptions used by the tool. Verify important results before making decisions or submitting official information.
How to Use This Tool
Use these steps to enter the right inputs and interpret the result correctly.
Choose the percentage calculation you need.
Enter the values shown for that calculation mode.
Press Calculate Percentage to see the main answer.
Review the formula, substitution, and short explanation.
Switch modes when you need increase, decrease, change, or difference instead.
Related Tools
Other helpful tools for percentages, discounts, taxes, tips, and quick calculations.
Percentage Increase Calculator
Calculate the final value after a percentage increase.
Percentage Decrease Calculator
Calculate the final value after a percentage decrease.
Percentage Change Calculator
Calculate percentage increase or decrease.
Discount Calculator
Calculate sale price, amount saved, discount percentage, and final price after sales tax.
Sales Tax Calculator
Calculate sales tax, price after tax, pre-tax price, and checkout totals from an entered rate.
Tip Calculator
Calculate tips, split bills, compare common percentages, and handle before-tax or after-tax tipping.
Profit Margin Calculator
Calculate profit margin, markup, selling price, revenue, cost, and pricing scenarios.
ROI Calculator
Calculate ROI, net gain, return multiple, annualized ROI, and project return scenarios.
Scientific Calculator
A full-featured scientific calculator in your browser.
Related Guides
Background reading and explanations related to Percentage Calculator.
Frequently Asked Questions
Common questions about Percentage Calculator and how to read the result.
What is a percentage?
A percentage is a number expressed out of 100. For example, 25% means 25 out of 100.
How do I calculate a percentage of a number?
Convert the percentage to a decimal by dividing by 100, then multiply by the number.
How do I calculate percentage increase?
Subtract the original value from the new value, divide by the original value, then multiply by 100.
How do I calculate percentage decrease?
Subtract the new value from the original value, divide by the original value, then multiply by 100.
What is the difference between percentage change and percentage difference?
Percentage change compares an old value to a new value. Percentage difference compares two values using their average as the reference.
What is the difference between percentage and percentage points?
A percentage is a relative amount. Percentage points describe the direct difference between two percentages, such as 20% to 30% being 10 percentage points.
Why do I multiply by 100?
Multiplying by 100 converts a decimal ratio into a percentage, which means out of 100.
Can percentages be greater than 100?
Yes. A percentage above 100 means the amount is greater than the base value.
Can percentage change be negative?
Yes. A negative percentage change means the value went down from the old value.
Are the results rounded?
Results are formatted for readability, usually up to four decimal places.