Math & Statistics
Percentage Calculator – Calculate Percentage Online
Easily calculate percentages, percentage increase or decrease, and find what percent one number is of another using our free online Percentage Calculator. Fast, accurate, and simple tool for everyday use.
Understanding Percentages
A percentage is a number expressed as a fraction of 100. The word comes from Latin per centum, meaning "by the hundred." The basic formula is: Percentage = (Part ÷ Whole) × 100. For example, 30 out of 120 = (30 ÷ 120) × 100 = 25%.
Percentages are used everywhere — discounts, taxes, tips, grades, interest rates, statistics, and growth rates. This calculator handles four common percentage operations: finding a percentage of a number, determining what percent one number is of another, calculating percentage change, and adding/subtracting a percentage.
What is X% of Y?
X is what % of Y?
Percentage Change
Add / Subtract Percentage
How to Use This Calculator
- Choose the type of percentage calculation you need from the four cards above
- Enter the required numbers in the input fields
- Click the Calculate button (or Increase/Decrease for the add/subtract card)
- View the result instantly with the formula applied
Common Use Cases
- Shopping discounts: Find the sale price — "What is 25% of $80?" gives you the $20 discount
- Exam grades: Convert scores — "42 is what % of 50?" gives you 84%
- Price changes: Track inflation — percentage change from $3.50 to $4.20 shows a 20% increase
- Tax calculation: Add sales tax — "$50 + 8%" gives you $54 total
- Tip calculation: Find the tip — "What is 18% of $75?" gives you $13.50
- Salary raises: Calculate new salary — "$60,000 + 5%" gives you $63,000
Percentage Formulas Quick Reference
| Calculation | Formula | Example | Result |
|---|---|---|---|
| X% of Y | (X / 100) × Y | 20% of 150 | 30 |
| X is what % of Y | (X / Y) × 100 | 45 of 180 | 25% |
| % Change | ((New − Old) / Old) × 100 | 80 → 100 | +25% |
| % Increase | Value × (1 + %/100) | 200 + 15% | 230 |
| % Decrease | Value × (1 − %/100) | 200 − 15% | 170 |
| Reverse % | Final / (1 + %/100) | 230 before 15% markup | 200 |
Common Percentages of Popular Numbers
| Number | 10% | 15% | 20% | 25% | 33⅓% | 50% | 75% |
|---|---|---|---|---|---|---|---|
| 50 | 5 | 7.5 | 10 | 12.5 | 16.67 | 25 | 37.5 |
| 100 | 10 | 15 | 20 | 25 | 33.33 | 50 | 75 |
| 200 | 20 | 30 | 40 | 50 | 66.67 | 100 | 150 |
| 500 | 50 | 75 | 100 | 125 | 166.67 | 250 | 375 |
| 1,000 | 100 | 150 | 200 | 250 | 333.33 | 500 | 750 |
Real-World Percentage Applications
| Scenario | Calculation | Example |
|---|---|---|
| Store discount | Price × (Discount% / 100) | $80 shirt at 25% off → save $20, pay $60 |
| Sales tax | Price × (1 + Tax%/100) | $50 item + 8% tax → $54 |
| Restaurant tip | Bill × (Tip%/100) | $75 bill, 18% tip → $13.50 tip |
| Exam grade | (Score / Total) × 100 | 42 out of 50 → 84% |
| Salary raise | Salary × (1 + Raise%/100) | $60,000 + 5% raise → $63,000 |
| Investment return | ((End − Start) / Start) × 100 | $10,000 → $11,200 = +12% return |
FAQ – Percentage Calculator
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. Formula: (X% ÷ 100) × Y. Example: 20% of 150 = (20 ÷ 100) × 150 = 0.20 × 150 = 30. A quick shortcut: to find 10%, just move the decimal point one place left (150 → 15), then double it for 20% (15 × 2 = 30).
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. Formula: (Part ÷ Whole) × 100. Example: 45 is what percent of 180? → (45 ÷ 180) × 100 = 25%. This works for grades, proportions, statistics, and any part-to-whole comparison.
What is percentage change and how is it calculated?
Percentage change measures how much a value increased or decreased relative to its original value. Formula: ((New − Old) ÷ Old) × 100. If the result is positive, it's an increase; if negative, a decrease. Example: price went from $80 to $100 → ((100 − 80) ÷ 80) × 100 = 25% increase.
How do I reverse a percentage to find the original number?
If you know the final value after a percentage was added, divide by (1 + %/100). Example: a product costs $115 after 15% markup — original price = $115 ÷ 1.15 = $100. For a discount: divide by (1 − %/100). A $68 item after 15% off → $68 ÷ 0.85 = $80 original.
What's the difference between percentage and percentile?
A percentage is a fraction of 100 (e.g., you scored 85%). A percentile indicates your rank relative to others (e.g., 90th percentile means you scored higher than 90% of people). Percentage measures a value; percentile measures position in a distribution.
How do I calculate percentage increase and decrease?
For increase: New Value = Original × (1 + %/100). For decrease: New Value = Original × (1 − %/100). Example: $200 increased by 15% = $200 × 1.15 = $230. $200 decreased by 15% = $200 × 0.85 = $170. Note: a 15% increase followed by a 15% decrease does NOT return to the original ($230 × 0.85 = $195.50).
How do I convert between fractions, decimals, and percentages?
Fraction → Decimal: divide numerator by denominator (3/4 = 0.75). Decimal → Percentage: multiply by 100 (0.75 = 75%). Percentage → Fraction: put over 100 and simplify (75% = 75/100 = 3/4). Percentage → Decimal: divide by 100 (75% = 0.75).
Why doesn't a 50% increase followed by a 50% decrease give the original?
Because the decrease applies to the larger number, not the original. Example: 100 + 50% = 150. Then 150 − 50% = 75, not 100. The decrease of 50% is calculated on 150 (which is 75), not on 100 (which would be 50). This is a common misconception in percentage math.
How do I calculate compound percentage changes?
Multiply the growth factors together. Example: 10% increase then 20% increase = 1.10 × 1.20 = 1.32, or 32% total increase (not 30%). For annual compound growth: Final = Initial × (1 + rate)^years. $1,000 at 5% for 3 years = $1,000 × 1.05³ = $1,157.63.
What are percentage points vs. percentages?
A percentage point is an absolute difference between two percentages. If interest rates go from 3% to 5%, that's a 2 percentage point increase but a 66.7% increase in the rate itself ((5−3)/3 × 100). Media often confuses these — "unemployment rose 2 percentage points" is very different from "unemployment rose 2%."