Percentage Calculator

Common percentage calculations between two numbers.

The Percentage Calculator handles the common percentage calculations between two numbers right in your browser. Choose a mode to find A% of B, work out what percent A is of B, or measure the percentage change from A to B. It's a quick way to get accurate percent and ratio results without reaching for a spreadsheet or formula.

Common uses

  • Calculate a discount or tax amount as A% of a base value B
  • Find what percentage one number represents of another (A is what % of B)
  • Measure growth or decline as the percentage change from an old value A to a new value B
  • Sanity-check percentages in invoices, reports, or test data
  • Convert a raw ratio of two figures into a clean percentage

FAQ

Is my data sent to a server?

No. The calculator runs entirely in your browser and nothing you type is uploaded. All math happens locally on your device.

What are the three modes?

"A% of B" returns (A / 100) * B, "A is what % of B" returns (A / B) * 100, and "% change from A to B" returns ((B - A) / A) * 100. You pick the mode from the dropdown and enter both values.

How are results rounded?

Results are rounded to a maximum of four decimal places. Trailing zeros are dropped, so a clean number like 25 shows as 25 rather than 25.0000.

Why do I sometimes get an error about a value being zero?

In "A is what % of B" mode, B cannot be zero because it is the divisor. In "% change from A to B" mode, A cannot be zero for the same reason. You will also see an error if either value is not a valid number.

Can I enter decimals or negative numbers?

Yes. Both values are parsed as floating-point numbers, so decimals and negatives are accepted as long as the divisor in your chosen mode is not zero.

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