Percentage Calculator - Every Percent Problem
From finding 20% off to calculating percentage change and reverse percentages, this calculator handles every type of percent problem instantly. Perfect for shopping, finance, tips, and homework.
Types of Percentage Problems
| Problem Type | Formula |
|---|---|
| X% of Y | (X ÷ 100) × Y |
| X is what % of Y | (X ÷ Y) × 100 |
| % increase | ((New - Old) ÷ Old) × 100 |
| % decrease | ((Old - New) ÷ Old) × 100 |
| Reverse percentage | Value ÷ (1 + Rate) |
| Percent difference | |X - Y| ÷ ((X + Y) ÷ 2) × 100 |
Common Examples
- 20% of $85 = $17
- 15 is what percent of 60? = 25%
- $120 to $150 = 25% increase
- $150 to $120 = 20% decrease
- $80 after 20% off = $100 original
- Percent difference between 40 and 60 = 40%
Everyday Percentage Uses
- Calculating tips (15-20%)
- Finding sale prices and discounts
- Understanding sales tax
- Computing grade improvements
- Interest rates and APR
- Body fat and fitness metrics
- Investment returns and portfolio performance
- Nutrition labels (% daily value)
Quick Mental Math Tricks
- 10%: Move the decimal one place left
- 5%: Take 10% and divide by 2
- 15%: Take 10% plus 5%
- 20%: Double the 10% value
- 25%: Divide by 4
- 50%: Divide by 2
- 1%: Move decimal two places left
Frequently Asked Questions
How do I calculate a percentage?
Divide the part by the whole and multiply by 100. Example: 20 ÷ 80 × 100 = 25%.
How do I calculate percent change?
(New value - Old value) ÷ Old value × 100.
What is the difference between percentage and percentile?
Percentage is a fraction out of 100. Percentile is a rank compared to a group (e.g., 90th percentile = top 10%).
What is percentage point vs percent?
A percentage point is a direct difference (5% to 7% = 2 percentage points). A percent change is relative (5% to 7% = 40% increase).
How do I calculate a discount?
Original × (1 - discount%) = final price. 20% off $80 = $80 × 0.80 = $64.
How do I find the original price after a discount?
Final price ÷ (1 - discount%). $64 ÷ 0.80 = $80 original.