How do I calculate a percentage increase?

Use the “% change” mode: (new − old) ÷ old × 100. Going from 80 to 100 is a 25% increase.

Why is a 50% increase not undone by a 50% decrease?

Because the base changes: 100 + 50% = 150, but 150 − 50% = 75. Percentage changes always apply to the current value, not the original.

How do I work out a discount price?

Use “What is X% of Y?” with the discount rate, then subtract. A 30% discount on $80: 30% of 80 = 24, so you pay $56.

Percentage Calculator

Three percentage calculators in one: find X% of a number, what percent X is of Y, and the percentage change between two values.

What is X% of Y?

% of = —

X is what percent of Y?

is what % of = —

Percentage change

From to = —

How to use the Percentage Calculator

Pick the question you need: “What is X% of Y?”, “X is what % of Y?” or “% change from X to Y”.
Enter your two numbers — the answer appears instantly.
Results are rounded to two decimal places where needed.

About this tool

Percentages show up everywhere — discounts, tips, taxes, interest, grade weightings, growth metrics — but each situation phrases the question differently. This calculator covers the three forms nearly every percentage problem reduces to.

“What is 15% of 240?” multiplies the base by the rate (36). “18 is what percent of 120?” divides the part by the whole (15%). “% change from 50 to 62” compares two values against the original (a 24% increase). Type numbers, get the answer — no formula juggling.

The tool also shows the formula it used with your numbers substituted in, so it doubles as a quick refresher when you want to redo the calculation mentally or in a spreadsheet later.

Frequently asked questions

How do I calculate a percentage increase?: Use the “% change” mode: (new − old) ÷ old × 100. Going from 80 to 100 is a 25% increase.
Why is a 50% increase not undone by a 50% decrease?: Because the base changes: 100 + 50% = 150, but 150 − 50% = 75. Percentage changes always apply to the current value, not the original.
How do I work out a discount price?: Use “What is X% of Y?” with the discount rate, then subtract. A 30% discount on $80: 30% of 80 = 24, so you pay $56.

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