Percentage Calculator
Calculate percentages easily — what is X% of Y, X is what % of Y, and percentage change.
What Is a Percentage Calculator?
A percentage calculator is a quick math utility that handles the three most common percentage problems people encounter in everyday life — from calculating discounts and tips to tracking growth metrics and test scores.
This tool supports three distinct calculation modes:
- What is X% of Y? — Find a specific percentage of a number (e.g., what is 15% of 250?).
- X is what % of Y? — Determine what percentage one number represents of another (e.g., 45 is what % of 180?).
- Percentage change from A to B — Calculate how much a value has increased or decreased as a percentage (e.g., from 80 to 100 = 25% increase).
Each mode displays the exact formula used so you can understand the math behind every result.
How to Use This Percentage Calculator
Using this tool is fast and straightforward:
- Select a tab matching the type of percentage problem you want to solve.
- Enter your numbers in the input fields — results update instantly as you type.
- Read the result along with the formula applied, so you understand the calculation.
- Copy the result to your clipboard with one click.
- Use the Clear button to reset any panel and start fresh.
No need to press "Calculate" — answers appear the moment both required values are filled in.
Common Use Cases for Percentage Calculations
- 🛍️ Shopping discounts — Calculate how much you save with a 20% off sale.
- 📊 Business & finance — Track revenue growth, profit margins, and budget allocations.
- 🎓 Grades & scores — Find out what percentage you scored on a test (e.g., 42 out of 50).
- 💰 Tips & splits — Quickly compute a restaurant tip or shared bill percentage.
- 📈 Data analysis — Measure the percentage change between data points over time.
- 🏋️ Fitness goals — Track progress toward a weight or performance target.
- 🏦 Interest & loans — Estimate simple interest or loan payment percentages.
Frequently Asked Questions
What is the formula for finding X% of Y?
The formula is: Result = (X / 100) × Y. For example, 25% of 200 = (25 / 100) × 200 = 50.
How do I find what percentage X is of Y?
Divide X by Y, then multiply by 100: Percentage = (X / Y) × 100. For example, 50 is what % of 200? Answer: (50 / 200) × 100 = 25%.
What is the formula for percentage change?
Percentage change = ((B − A) / |A|) × 100. A positive result means an increase; a negative result means a decrease.
Can the original value (A) be zero for percentage change?
No — dividing by zero is mathematically undefined. If the original value is 0, percentage change cannot be calculated. The tool will display an error in this case.
Does this calculator handle negative numbers?
Yes. All three calculators accept negative input values. For example, a percentage change from −50 to −25 will correctly compute as a 50% increase (the value moved closer to zero).
How many decimal places does the result show?
Results are rounded to up to 6 significant decimal places to balance precision and readability. Whole-number results display without trailing decimals.