Math & School

Percent calculator

Percentage, percentage, base value or change - one mask, four cases.

Updated on Apr 21, 2026 Calculator, calculation path and examples on one page

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Calculator

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Calculation path

Step by step

  1. Calculate percentage

    Formula: p = W / G × 100

    Values inserted: 47.50 / 250.00 × 100

    Result: 19.00%

Instructions

How to use this calculator correctly

How to use the calculator

  • Choose the appropriate mode.
  • Fill in only the values ​​that this mode needs.
  • Read the result and calculation method directly.

Common mistakes

  • Swap basic value and percentage value.
  • Calculate change with incorrect initial value.

Limits of the calculation

  • The computer works mathematically precisely, but without any special technical rules.

Related guide: Solve the rule of three, percentage calculations and fractions in an understandable way

Examples

Typical calculations

FAQ

Frequently asked questions

What is the difference between basic value and percentage value?

The basic value is the whole set. The percentage is the proportion of it.

Can the calculator also show negative changes?

Yes. If the new value decreases, a negative percentage change is output.

Which mode do I use for price increases?

Select the percentage change mode and enter the old and new values.

How do I calculate 19 percent of 250?

In Percentage mode with base value 250 and percentage 19.

Why is the old value important in change?

Because the percentage change always refers to the initial value.

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Sources and notes

Rule status and context

Formulas
W = G × p / 100, p = W / G × 100, G = W / (p / 100), change = (new − old) / old × 100