Percentage Calculator – % Of, Change & Reverse

Free percentage calculator: find X% of Y, what percent A is of B, percentage increase/decrease, and reverse percentages — instant math, no signup.

Private: calculation runs only in your browser.

Percentage Calculator

Free percentage calculator: find X% of Y, what percent A is of B, percentage increase/decrease, and reverse percentages — instant math, no signup.

Percent (%)

Of number

15% of 80

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What Is a Percentage Calculator?

A percentage calculator solves everyday percent problems: how much is X% of a number, what percent one value is of another, and how much a value grew or shrank in percent terms. Use it for grades, tips, discounts, and growth rates.

Core Percent Formulas

X% of Y = Y × (X ÷ 100)

A is % of B = (A ÷ B) × 100

% change = ((New − Old) ÷ Old) × 100

Frequently Asked Questions

How do you calculate a percentage of a number?

Multiply by percent ÷ 100. Example: 15% of 80 = 12.

How do you calculate percentage increase?

((New − Old) ÷ Old) × 100. From 50 to 65 is a 30% increase.

What is a reverse percentage?

Finding the original before a % was applied — e.g. $80 after 20% off → $100 original.

Is this percentage calculator free?

Yes — free and private.