Percentage Calculator
Calculate increases, discounts, and proportions instantly.
Enter values to calculate
Percentage Formula Cheat Sheet
Percentage Increase Formula
Example: Moving from $50 to $75 is a 50% increase.
"Percentage Of" Formula
Example: 20% of $500 is $100.
Real-World Applications
Discounts & Sales
Calculate the final price of an item on sale. 25% off a $80 jacket means you save $20 and pay $60.
Investment Growth
Track your portfolio performance. If you bought for $1,000 and sold for $1,500, calculate your 50% ROI.
Tips & Tax
Calculate a 20% tip on a bill ($50 bill = $10 tip) or add 8% sales tax to a purchase.
Inflation Calculator
Determine how much purchasing power has decreased over time using the percentage decrease mode.
Weight Loss
Track progress by calculating percentage of body weight lost over time.
Markup & Margin
For business owners, calculate the markup percentage needed to achieve a specific profit margin.
Mastering Percentages: Beyond the Calculator
⚠️ The "Percentage Point" Trap
Moving from 5% to 7% is NOT a 2% increase. It is a 2 percentage point increase, but a 40% relative increase in the underlying rate.
Formula: ((7 - 5) / 5) * 100 = 40%
🔄 Reverse Percentages
If a price is $120 after a 20% tax, the original price was NOT $100. It was $100.
Wrong: 120 - 20% = 96
Right: 120 / 1.20 = 100
Why "Percent" Means "Per 100"
The word comes from the Latin per centum, literally meaning "by the hundred". It is a standardized way of expressing fractions. 0.5, 1/2, and 50% are mathematically identical values represented in different formats.
How to Calculate Percentages in Your Head
While this calculator is instant, knowing these mental math tricks is useful:
- 10%: Move the decimal point one spot to the left (10% of 500 is 50).
- 1%: Move the decimal point two spots to the left (1% of 500 is 5).
- 5%: Find 10%, then cut it in half.
- 15%: Find 10%, find 5%, and add them together.
Percentage Change vs. Percentage Difference
It is crucial to choose the right calculation for your specific scenario.
| Feature | Percentage Change | Percentage Difference |
|---|---|---|
| Goal | Track growth/loss over time | Compare two separate items |
| Order Matters? | Yes (Old vs New) | No (A vs B) |
| Common Use | Stock prices, Weight loss, Inflation | Comparing prices of two laptops |
| Formula | (New - Old) / Old | |A - B| / ((A + B) / 2) |
| Result | Can be Positive or Negative | Always Positive |
How to Use This Percentage Calculator
Select Calculation Mode
Choose 'Increase/Decrease' for growth, 'What is X% of Y' for parts, or 'X is what % of Y' for proportions.
Enter Values
Input your starting numbers. For percentage increase, ensure you put the 'Original' value first.
View Result
The answer appears instantly. Positive numbers indicate an increase, negative numbers indicate a decrease.
Read Explanation
Check the sentence below the result to confirm you are interpreting the data correctly.
Frequently Asked Questions
How do calculate percentage increase?
Subtract the original number from the new number, divide the result by the original number, and multiply by 100. Formula: ((New - Old) ÷ Old) × 100.
How do I calculate a 20% discount?
To calculate a 20% discount, multiply the original price by 0.20 to find the savings, then subtract that from the original price. Or simply multiply the price by 0.80 to get the final cost.
What is the formula for percentage difference?
Percentage difference compares two values. Formula: |V1 - V2| ÷ ((V1 + V2) ÷ 2) × 100. This is best used when neither value is the 'original' reference point.
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