Percentage Calculator
Calculate Percentage
Quick Examples
Percentage Of: 25 is 12.5% of 200
Percent Of: 15% of 200 is 30
Increase: 50 to 75 is 50% increase
Decrease: 100 to 75 is 25% decrease
Select calculation type and enter values
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Similar Tools
15% of 240 — and Why +15% Is Not −15%
15% of 240 is 36 — the classic 'what is X% of Y'. Reverse direction: 45 is exactly 25% of 180. Change calculations behave asymmetrically: a price moving from 80 to 92 rose 15%, but falling from 92 back to 80 is a 13.04% drop, because the percentage is measured against the starting value each time. Same two numbers, different baselines, different answers.
Percentage Points Are Not Percentages
When an interest rate moves from 4% to 5%, that is one percentage point, not one percent — relatively speaking it is a 25% increase. Two consecutive 10% price increases do not total 20% but 21%, because the second rise applies to the already-raised price. And a percentage change from zero is mathematically undefined, which is why the tool refuses 'old value = zero' instead of returning a meaningless number.
About Percentage Calculator
Shoppers calculating the final price after a discount, tenants checking whether a rent increase exceeds a legal percentage cap, marketers reporting how much a conversion rate improved, and students checking exam marks against a total — all of these are the same three calculations: a percentage of a value, a value as a percentage of another, and the change between two values. Which one applies depends entirely on what you know and what you want.
How to Use
Step 1
Select the calculation type from the dropdown menu
Step 2
Enter the first value (value, percentage, or old value)
Step 3
Enter the second value (total, value, or new value)
Step 4
Click 'Calculate' to see the result
Step 5
View the result with percentage or final value
Step 6
Read the explanation in plain English
Step 7
Check the formula to understand the calculation
Step 8
Use quick examples for common scenarios
Features & Benefits
- ✅9 percentage calculation types in one tool
- ✅What percentage is X of Y? (e.g., 25 is what % of 200?)
- ✅What is X% of Y? (e.g., what is 15% of 200?)
- ✅Percentage increase calculator (old to new value)
- ✅Percentage decrease calculator (old to new value)
- ✅Percentage change calculator (increase or decrease)
- ✅Value after percentage increase (e.g., 100 + 20%)
- ✅Value after percentage decrease (e.g., 100 - 20%)
- ✅Percentage difference between two values
- ✅Find the whole from a percentage (reverse calculation)
- ✅Shows formula for each calculation type
- ✅Plain English explanation of result
- ✅Quick examples for common scenarios
- ✅Supports decimal values (e.g., 12.5, 33.33)
- ✅Clear button to reset calculator
- ✅100% browser-based - data never sent to server
- ✅100% free - no limits, no signup required
FAQs
How do I calculate what percentage one number is of another?
Use 'What % is X of Y?' calculation. Divide the first number by the second, then multiply by 100. For example: 25 is what % of 200? = (25 / 200) × 100 = 12.5%. This is useful for calculating grades, completion rates, or proportions.
How do I calculate a percentage of a number?
Use 'What is X% of Y?' calculation. Divide the percentage by 100, then multiply by the number. For example: What is 15% of 200? = (15 / 100) × 200 = 30. This is useful for calculating discounts, tips, taxes, or commissions.
What's the difference between percentage increase and percentage change?
Percentage increase only works when the new value is greater than the old value (positive change). Percentage change works for both increases and decreases, showing positive for increase and negative for decrease. Use increase/decrease for specific directions, or change for any direction.
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value, then multiply by 100. For example: From 50 to 75 = ((75 - 50) / 50) × 100 = 50% increase. This is useful for price increases, growth rates, or salary raises.
How do I calculate percentage decrease?
Subtract the new value from the old value, divide by the old value, then multiply by 100. For example: From 100 to 75 = ((100 - 75) / 100) × 100 = 25% decrease. This is useful for discounts, weight loss, or price reductions.
What's the difference between percentage decrease and percentage difference?
Percentage decrease compares change relative to the original value (old value). Percentage difference compares the absolute difference relative to the average of both values. Decrease is directional (old to new), while difference is symmetric (works either way).
How do I calculate the final price after a discount?
Use 'Value After Decrease' calculation. For example, if an item costs $100 and has a 20% discount: 100 - (100 × 20 / 100) = $80. Or use 'What is X% of Y?' to find the discount amount (20% of 100 = 20), then subtract from original price.
How do I find the original price before a discount?
Use 'Find the Whole' calculation. If the sale price is $80 after a 20% discount, the item is 80% of the original price. So: (80 / 80) × 100 = $100 original price. This reverse calculation finds 100% when you know a percentage and its value.
Can I calculate percentages with decimal numbers?
Yes! The calculator supports decimal values like 12.5, 33.33, or 0.5. This is useful for precise calculations like 12.5% tax, 33.33% ownership, or 0.5% interest rates. Results are rounded to 2 decimal places for readability.
What if I get an error message?
Common errors: 'Total cannot be zero' (can't divide by zero), 'Old value cannot be zero' (can't calculate percentage change from zero), 'New value must be greater' (for increase) or 'less' (for decrease). Check your values and calculation type.
Is my data secure?
Yes! All percentage calculations happen entirely in your browser using JavaScript. Your numbers and results never leave your device and are not sent to any server, ensuring complete privacy and security.