Percentage Calculator
Three calculators in one — find percentages, reverse-calculate, and compute percentage change instantly.
💯 What is X% of Y?
Quick Reference — Common Percentages
| % | of 100 | of 200 | of 500 | of 1,000 |
|---|---|---|---|---|
| 1% | 1 | 2 | 5 | 10 |
| 5% | 5 | 10 | 25 | 50 |
| 10% | 10 | 20 | 50 | 100 |
| 15% | 15 | 30 | 75 | 150 |
| 20% | 20 | 40 | 100 | 200 |
| 25% | 25 | 50 | 125 | 250 |
| 30% | 30 | 60 | 150 | 300 |
| 40% | 40 | 80 | 200 | 400 |
| 50% | 50 | 100 | 250 | 500 |
| 75% | 75 | 150 | 375 | 750 |
Common Percentage Answers — Instant Reference
The most frequently searched percentage questions, answered at a glance.
💯 % of 100
💯 % of 200
💯 % of 1,000
📈 % Change Examples
How to Calculate a Percentage of a Number
To find X% of Y, use the formula: Result = (X ÷ 100) × Y. For example, to find 15% of 200: (15 ÷ 100) × 200 = 0.15 × 200 = 30.
A quick mental shortcut: to find 10%, just move the decimal point one place left. To find 5%, halve that. To find 20%, double the 10% value. For example, 10% of 350 = 35, so 20% of 350 = 70 and 5% of 350 = 17.5.
Real-World Examples
Tips: A 20% tip on a $45 meal = $9. (45 × 0.20 = 9)
Discounts: 25% off a $120 item = $30 savings, so you pay $90.
Tax: 8.5% sales tax on a $200 purchase = $17 in tax.
Finance: 3% annual interest on a $10,000 investment = $300 per year.
How to Find What Percentage One Number Is of Another
To find what percent X is of Y, use: Percentage = (X ÷ Y) × 100. For example, 40 is what percent of 200? (40 ÷ 200) × 100 = 20%.
This is useful for calculating test scores (you got 42 out of 50 — that's (42 ÷ 50) × 100 = 84%), market share, nutritional info, and more.
Percentage Change Formula
Percentage change measures how much a value has grown or shrunk relative to its starting point:
% Change = ((New Value − Original Value) ÷ Original Value) × 100
A positive result is a percentage increase; a negative result is a percentage decrease. For example, a price rises from $80 to $100: ((100 − 80) ÷ 80) × 100 = (20 ÷ 80) × 100 = 25% increase.
Percentage Increase vs. Decrease
Note that a 25% increase followed by a 25% decrease does not return to the original value. If you start at 100, +25% = 125, then −25% of 125 = 93.75. This asymmetry is important in finance and statistics.
Frequently Asked Questions
- How do I calculate a percentage of a number?
- Multiply the number by the percentage, then divide by 100. Example: 15% of 200 = (200 × 15) ÷ 100 = 30.
- What is the percentage change formula?
- % Change = ((New − Original) ÷ Original) × 100. A positive result is an increase; negative is a decrease. Example: 80 to 100 = ((100 − 80) ÷ 80) × 100 = 25% increase.
- How do I find what percentage one number is of another?
- Divide the part by the whole, then multiply by 100. Example: 40 is what % of 200? (40 ÷ 200) × 100 = 20%.
- What is 10% of 1000?
- 10% of 1000 = 100. Calculated as (10 ÷ 100) × 1000 = 100.
- What is 20% of 50?
- 20% of 50 = 10. Calculated as (20 ÷ 100) × 50 = 10.