Percentage Calculator

What percent one number is of another, how much X% of a number is, and how big a change is. Fill in two fields and the calculator works out the third.

Business

A is X% of B

A auto is X% auto % of B auto

B is X% larger / smaller than A

A auto changes

X% auto % and the result is B auto

Results are informational. Calculation is based on your input and public rules, official accounting may differ. For accuracy, confirm the final result if needed from the appropriate official source or specialist. See the terms of use.

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How it works?

This calculator has two independent panels, each using a fill-any-two model: enter any two values and the third is computed instantly. The calculated field is marked auto. Edit that field at any time - it becomes a normal input and the oldest entry becomes the new computed field.

Panel 1 (A is X% of B) answers questions such as: 25 is what percent of 200? or What is 15% of 80? The math is X = (A ÷ B) × 100, A = B × X ÷ 100, or B = A × 100 ÷ X depending on which field is empty.

Panel 2 (Percentage change) computes the relative difference between two numbers. The larger / smaller toggle sets the direction when X% is entered manually. When A and B are both provided, the toggle is set automatically based on whether B exceeds A or not, and X% is shown as a positive value.

Frequently asked questions

How do I find what percentage A is of B?

Use Panel 1. Enter the values for A and B and leave X% empty - it is computed automatically as (A ÷ B) × 100. For example, enter A = 25 and B = 200 to get X = 12.5%.

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How do I calculate X% of a number?

Use Panel 1. Enter the percentage in X% and the base number in B, then leave A empty. It computes as B × X ÷ 100. For example, X = 20 and B = 150 gives A = 30.

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How do I find the percentage change from one number to another?

Use Panel 2. Enter the starting value in A and the ending value in B, then leave X% empty. The calculator shows the percentage change and sets the 'larger' or 'smaller' toggle automatically. For example, A = 80 and B = 100 gives +25% larger.

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What does the 'larger / smaller' toggle do in Panel 2?

The toggle controls the direction of the change when X% is one of the two inputs. 'Larger' means B = A × (1 + X ÷ 100); 'smaller' means B = A × (1 − X ÷ 100). When A and B are both entered, the toggle sets itself automatically.

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Can I use commas as decimal separators?

Yes - both commas and dots are accepted as decimal separators. The calculator normalises them automatically, so 1,5 and 1.5 are treated identically.

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