Percentage Calculator
Calculate percentages, percentage change, increase, decrease, and difference between two values instantly.
About Percentage Calculator
A percentage calculator is a mathematical tool that computes percentage values, increases, decreases, and differences. Percentages are used everywhere — from calculating sales tax and restaurant tips to analyzing financial growth and academic grades. Understanding how percentages work is essential for making informed decisions in everyday life, business, and academics.
How to Use
To use this tool, select the type of percentage calculation you need: find a percentage of a number (e.g., 15% of 200), calculate what percentage one number is of another (e.g., 30 is what % of 150?), find percentage increase or decrease between two values, or determine the percentage difference. Enter your values in the input fields and the result appears instantly. No formula memorization needed — the calculator handles all the math for you.
Formula / Key Equations
The core formulas are: Percentage of a number: (percentage / 100) × number. Percentage increase: ((new value - old value) / old value) × 100. Percentage decrease: ((old value - new value) / old value) × 100. Percentage difference: |a - b| / ((a + b) / 2) × 100.
Common Use Cases
Common use cases include: calculating sales tax on purchases, determining tip amounts at restaurants, figuring out discount prices during sales, analyzing year-over-year revenue growth, calculating grade improvements, and comparing price changes between products or services.
Limitations
This calculator works with standard decimal numbers. It cannot handle complex statistical percentages, compound percentage changes over multiple periods (for that, use a compound interest calculator), or fractional percentages beyond standard precision. Results are rounded to a reasonable number of decimal places.
Frequently Asked Questions
What is the difference between percentage increase and percentage difference?
Percentage increase measures growth from an old value to a new value using the old value as the base. Percentage difference measures the relative difference between two values without designating either as the base — it uses the average of both values instead.
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 25% of 80 = (25/100) × 80 = 20. Our calculator does this instantly — just enter the percentage and the number.
Can I calculate compound percentage changes?
This calculator handles single-step percentage changes. For compound changes (e.g., a price that increases 10% then decreases 5%), you would need to apply each change sequentially or use a compound interest calculator.
How accurate are the results?
Results are calculated with full floating-point precision and typically displayed to 2-4 decimal places depending on the calculation type. The underlying math is exact.
Is this percentage calculator free?
Yes, completely free with no sign-up required. It runs entirely in your browser — no data is sent to any server.
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