Percentage Calculator

What is percentage calculator?

Percentages show up in discounts, taxes, interest, grades, test scores, growth rates and statistics. This calculator handles the three most common questions in one place.

Mode one answers questions like what is 20 percent of 150. Mode two answers what percent is 30 of 150. Mode three measures how much a value has increased or decreased, for example a price that rose from 80 to 100.

How to use the percentage calculator

1. Pick the type of question from the menu.
2. Enter Value A and Value B. The labels in the result explain how each is used.
3. The result updates as you type.

How the percentage calculator works

Percent of: A divided by 100, times B. Percent as a share: A divided by B, times 100. Percent change: B minus A, divided by the absolute value of A, times 100. A positive result is an increase and a negative result is a decrease.

Worked example

Common uses of the percentage calculator

• Working out a discount, markup or sales tax.
• Calculating exam scores and grade percentages.
• Measuring growth in sales, followers or savings.
• Comparing prices to see how much cheaper one option is.
• Understanding statistics in news stories and reports.

Tips and common mistakes

Percent change is not symmetrical. A fall from 100 to 50 is minus 50 percent, but a rise from 50 back to 100 is plus 100 percent.

When comparing two percentages, such as interest rates, talk about percentage points for the plain difference and percent for the relative difference.

Background: what to know before you rely on it

The word percent means per hundred. It comes from the Latin per centum. Percentages let us compare parts of different wholes on the same scale: 12 out of 50 and 30 out of 125 are different amounts but both are 24 percent. A common source of mistakes is the base. A 50 percent rise followed by a 50 percent fall does not return you to the start, because the second change applies to a bigger number. Another is mixing percent and percentage points. If an interest rate rises from 4 percent to 5 percent, it rose by one percentage point, which is a 25 percent relative increase.

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.