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Percentage Calculator

Calculate percentages instantly. Find what percent of a number is, calculate percentage change, find the original value, and more.

What is X% of Y?

% of

How to Use This Tool

  1. Choose the type of percentage calculation you need using the tabs: "X% of Y", "X is what % of Y", "Percentage Change", or "Find Original Value".
  2. Enter the two required numbers into the input fields for the selected mode.
  3. The result updates automatically as you type — no submit button needed.
  4. Read the result summary line for a plain-English restatement of the calculation.

Formula & How It Works

Percentage of a Number

Result = (X / 100) × Y

To find X% of Y, divide X by 100 and multiply by Y.

What Percent One Number Is of Another

Result = (X / Y) × 100

To find what percent X is of Y, divide X by Y and multiply by 100.

Percentage Change

Result = ((New − Old) / |Old|) × 100

Subtract the original value from the new value, divide by the absolute original value, then multiply by 100. A positive result is an increase, a negative result is a decrease.

Find Original Value

Original = Final / (1 + Change% / 100)

Divide the final value by one plus the percentage change (expressed as a decimal) to work backward to the original value.

Practical Examples & Common Use Cases

Example: 25% of 200

25% of 200 = (25 / 100) × 200 = 50.

Example: 80 to 100 Percentage Change

From 80 to 100: ((100 − 80) / 80) × 100 = (20 / 80) × 100 = 25% increase.

Example: Find Original Value

120 after a 20% increase: Original = 120 / (1 + 20/100) = 120 / 1.2 = 100.

Frequently Asked Questions

Multiply the number by the percentage and divide by 100. For example, 25% of 200 = (25 × 200) / 100 = 50.

Subtract the original from the new value, divide by the original, and multiply by 100. Example: from 80 to 100 → (100 − 80) / 80 × 100 = 25% increase.

Divide the final value by (1 + percentage/100). Example: if 120 is the result after a 20% increase, the original was 120 / 1.20 = 100.

A percentage point is an absolute difference. If something goes from 10% to 15%, it increased by 5 percentage points, but by 50% in relative terms.

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