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 |
How to Use This Percentage Calculator
Step 1: Choose which type of percentage calculation you need using the three tabs at the top: What is X% of Y? (e.g., "What is 15% of 200?"), X is what % of Y? (e.g., "40 is what percent of 200?"), or % Change (e.g., "What is the percentage change from 80 to 100?").
Step 2: Enter your numbers into the input fields. The result updates instantly as you type — no need to click a button.
Step 3: View the result along with the formula breakdown showing exactly how the calculation works. This makes it easy to understand the math and verify the answer.
Step 4: Use the quick-reference table below for the most commonly searched percentage answers, or bookmark this page for quick access anytime you need to calculate percentages for tips, discounts, taxes, grades, or financial analysis.
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.