Percentage Calculator
Calculate percentages instantly. Find a percent of a number, determine what percent one number is of another, or compute the percentage change between two values.
What is X% of Y?
The percentage to calculate
The number to find the percentage of
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How to Use the Percentage Calculator
Our percentage calculator provides three essential modes that cover virtually every percentage calculation you will ever need. Whether you are figuring out a discount at the store, calculating your test score, or tracking how much your investments have grown, this tool delivers the answer instantly as you type.
Mode 1: Percent of a Number answers the question “What is X% of Y?” This is the most common percentage calculation. Enter the percentage and the number, and the result appears immediately. The formula is straightforward: Result = (Percentage / 100) x Number. Use this mode to calculate tips (e.g., 18% of $85), discounts (e.g., 30% off $150), tax amounts, or any proportional value.
Mode 2: Number is % of answers the question “X is what percent of Y?” Enter any two numbers and instantly see the percentage relationship between them. The formula is: Percentage = (Number / Total) x 100. This is perfect for calculating grades (32 out of 40), completion rates, win percentages, or determining what proportion one value represents of another.
Mode 3: Percentage Change answers the question “What is the percentage change from X to Y?” It calculates how much a value has increased or decreased in percentage terms. The formula is: Percentage Change = ((New Value - Old Value) / |Old Value|) x 100. The result is displayed with a clear visual indicator showing whether the change is an increase or decrease. Use this mode to track stock price movement, salary raises, weight changes, or any before-and-after comparison.
All three modes update results in real time as you type, include visual progress bars for intuitive understanding, and support sharing via URL so you can send your calculation to anyone. The calculator handles edge cases like division by zero gracefully, and works with decimals and large numbers alike.
Frequently Asked Questions
How do I calculate a percentage of a number?
To find X% of Y, multiply Y by X and divide by 100. For example, 15% of 200 is (200 x 15) / 100 = 30. Our calculator does this instantly — just enter the percentage and the number, and the result updates in real time.
What is the formula for percentage change?
Percentage change is calculated as ((New Value - Old Value) / Old Value) x 100. A positive result indicates an increase, while a negative result indicates a decrease. For example, going from 80 to 100 is a 25% increase: ((100 - 80) / 80) x 100 = 25%.
What is the difference between percentage change and percentage difference?
Percentage change measures the relative change from an original value to a new value and has a direction (increase or decrease). Percentage difference compares two values without a defined direction, using the average of the two as the base: |A - B| / ((A + B) / 2) x 100. This calculator uses percentage change, which is more common for tracking real-world changes over time.
How do I convert a fraction to a percentage?
To convert a fraction to a percentage, divide the numerator by the denominator and multiply by 100. For example, 3/4 = 0.75 x 100 = 75%. You can use the 'Number is % of' mode in our calculator by entering the numerator as the number and the denominator as the total.
How do I reverse a percentage calculation?
To reverse a percentage and find the original number, divide the result by the percentage expressed as a decimal. For example, if you know that 30 is 15% of some number, divide 30 by 0.15 to get 200. Similarly, if an item costs $85 after a 15% discount, the original price is $85 / (1 - 0.15) = $100. Our calculator can verify these results across all three modes.