Percentage Difference Calculator

What is percentage difference calculator?

People use the phrase percentage difference for two different ideas. Percentage difference compares two values on equal terms and does not care which one comes first. Percentage change measures how much a value rose or fell from an old value to a new value.

This calculator shows both, so you can pick the one that fits your question and see how they differ.

How to use the percentage difference calculator

1. Enter the first number and the second number.
2. Press Calculate.
3. Read the percentage difference, the percentage change and whether the second number is higher or lower.

How the percentage difference calculator works

Percentage difference equals the absolute difference divided by the average of the two numbers, times 100. Percentage change equals the new value minus the old value, divided by the absolute old value, times 100.

Worked example

Common uses of the percentage difference calculator

• Comparing prices from two shops.
• Checking a rise or fall in sales.
• Comparing test results or measurements.
• Science lab reports.
• Salary or rent comparisons.

Tips and common mistakes

Use percentage change when there is a clear before and after, such as a price rise.

Use percentage difference when neither value is the reference, such as comparing two products.

Percentage change from zero cannot be calculated, because you cannot divide by zero.

Background: what to know before you rely on it

Percentage difference is common in science and engineering, where two measurements are compared without calling one of them the true value. Because it divides by the average, the result is symmetric. Percentage change is common in business and news, where a starting point exists. Mixing the two ideas is a frequent source of confusion. For example, a price that goes from 80 to 100 rose by 25 percent, but if it later falls from 100 back to 80, the drop is only 20 percent. The percentage difference between the two values is 22.22 percent whichever way you read them.

Private, free and fast

This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all calculators, or browse the full list of tools.

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Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. Financial results are estimates and exclude fees and taxes unless the tool says otherwise.