Percentage Calculator
Percentages are one of the most commonly used mathematical concepts in everyday life. A percentage represents a fraction of 100 and is used to express proportions, compare values, and communicate changes in a way that is universally understood. From shopping discounts to tax rates, percentages are everywhere.
This calculator handles all common percentage operations: finding what percentage one number is of another, calculating a percentage of a value, and determining percentage increase or decrease between two numbers. Mastering percentage calculations is essential for budgeting, data analysis, academic work, and countless professional tasks.
How it works
Percentage = (Part / Whole) × 100. To find a percentage of a value: Result = Value × (Percentage / 100). Percentage change = ((New - Old) / Old) × 100.
Use cases
- Calculating discounts and sale prices while shopping
- Determining tax amounts and tip percentages
- Analyzing data trends and percentage changes over time
- Computing grades, scores, and performance metrics
Frequently asked questions
How do I calculate the percentage of a number?
Multiply the value by the percentage divided by 100: Result = Value × (Percentage / 100). For example, 25% of 80 is 80 × 0.25 = 20. This works for any percentage, including values over 100% — 150% of 40 is 60.
How do I calculate percentage change between two numbers?
Use the formula Percentage change = ((New − Old) / Old) × 100. If a price goes from 50 to 65, the change is ((65 − 50) / 50) × 100 = 30%, an increase. A negative result means a decrease — going from 65 back to 50 is a change of about −23.1%, which shows increases and decreases are not symmetric.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100: Percentage = (Part / Whole) × 100. For example, 30 out of 120 is (30 / 120) × 100 = 25%. This is the same calculation used for test scores, market shares, and completion rates.
How do I calculate a discount percentage?
Multiply the original price by (1 − discount / 100) to get the final price. An item costing 80 with a 15% discount ends up at 80 × 0.85 = 68, saving you 12. To find the discount percentage from two prices, use ((Original − Sale) / Original) × 100.
What is the difference between percent and percentage points?
Percentage points measure the absolute difference between two percentages, while percent measures relative change. If an interest rate rises from 40% to 45%, that is an increase of 5 percentage points, but a relative increase of 12.5% ((45 − 40) / 40 × 100). Confusing the two is one of the most common percentage mistakes.