How to Use the Percentage Calculator
This calculator offers 4 different modes for common percentage calculations. Simply select the mode that matches your need:
- % of Number: Calculate what X% of Y equals (e.g., "What is 15% of 200?")
- What Percent: Find what percentage one number is of another (e.g., "30 is what % of 200?")
- % Change: Calculate percentage increase or decrease (e.g., "100 increased by 20%")
- Reverse %: Find the original number when you know the percentage (e.g., "30 is 15% of what?")
Common Use Cases
🛍️ Shopping Discounts
Calculate the final price after a discount. If something costs $50 and has a 20% discount, use "% Change" mode with decrease.
🍽️ Restaurant Tips
Calculate how much to tip. If your bill is $80 and you want to leave 15%, use "% of Number" mode.
💰 Sales Tax
Add sales tax to a price. If an item costs $100 and tax is 8%, use "% Change" mode with increase.
📊 Grade Percentages
Calculate your test score. If you got 42 out of 50 questions correct, use "What Percent" mode.
Percentage Formulas
Finding X% of Y
Result = (X ÷ 100) × Y
Example: 15% of 200 = (15 ÷ 100) × 200 = 30
Finding What % X is of Y
Result = (X ÷ Y) × 100
Example: 30 is what % of 200? = (30 ÷ 200) × 100 = 15%
Percentage Increase/Decrease
Result = Original ± (Original × Percentage ÷ 100)
Example: 100 increased by 20% = 100 + (100 × 20 ÷ 100) = 120
Frequently Asked Questions
How do I calculate a discount percentage? ▼
Use the "% Change" mode and select "Decrease". Enter the original price and the discount percentage. For example, a $100 item with 20% off would give you $80 as the final price.
What's the difference between percentage and percentile? ▼
A percentage is a fraction of 100 (e.g., 50% = 50/100). A percentile is a statistical measure indicating the value below which a percentage of data falls (e.g., 90th percentile means you scored better than 90% of others).
Is my data saved or sent to a server? ▼
No. All calculations happen entirely in your browser. Your numbers never leave your device, ensuring complete privacy.
Can I calculate multiple discounts? ▼
Yes, but apply them sequentially. For example, for 20% off then 10% off a $100 item: First calculate $100 - 20% = $80, then calculate $80 - 10% = $72. Note that this is NOT the same as 30% off!