Percentage Calculator

Calculate percentages, percentage change, increases, decreases and reverse percentages with step-by-step formulas.

Inputs save automatically on this device.
Your result will appear here.

Choose a calculation type and enter your values.

About the Percentage Calculator

Percentages show how one amount relates to another on a scale of 100. This calculator can find a percentage of a number, determine what percentage one value is of another and solve common increase, decrease or reverse-percentage questions without forcing you to rearrange the formula yourself.

The important part is identifying the base value. The same two numbers can produce different percentage statements depending on which one is treated as the original or reference amount.

How to Use the Percentage Calculator

  1. Choose the percentage problem that matches what you are trying to find rather than entering numbers into the first available fields.
  2. Enter the base or original value carefully. This is the quantity the percentage is measured against.
  3. Enter the percentage rate or comparison value requested by the selected mode.
  4. Calculate the result, then read the explanation to confirm which value was treated as the base.

How the Calculation Works

To find p% of a number N, convert the percentage to a decimal and multiply: result = N × p ÷ 100. To find what percentage A is of B, divide A by B and multiply by 100: percentage = A ÷ B × 100.

Percentage increase and decrease use the original value as the denominator. Reverse-percentage problems rearrange the relationship so the known final amount is divided by the remaining or increased percentage factor.

Worked example

Percentage Calculator Worked Example

15% of 240

Convert 15% to decimal form: 15 ÷ 100 = 0.15. Then multiply by the base value: 240 × 0.15 = 36. So 15% of 240 is 36.

Result guide

Understanding Your Percentage Calculator Result

A percentage result is only meaningful when the reference amount is clear. If you are comparing change over time, label the old and new values explicitly; reversing them changes the percentage because the denominator changes.

Before you rely on the answer

Assumptions and Limitations

  • The denominator or base value is the correct reference for the question.
  • Percentage comparisons involving a zero base cannot be handled as an ordinary finite percentage.
  • Displayed rounding may shorten a repeating decimal without changing the underlying relationship.

Practical tip

Using This Result in Practice

When a percentage answer seems surprising, recalculate it as a fraction of the base. For example, 25% should correspond to one quarter of the reference amount. This quick sense-check catches many swapped-input errors.

Related calculations

Useful Calculations to Continue With

If you are comparing an old value with a new value, the Percentage Change Calculator is a better fit because it keeps the original value explicit.

If your question is about the relationship between two quantities without converting to a scale of 100, use the Ratio Calculator.

Common questions

Percentage Calculator FAQ

What is the difference between percentage and percentage change?

A percentage describes a part relative to a base. Percentage change specifically compares a new value with an original value and uses the original value as the denominator.

Why is a 20% increase followed by a 20% decrease not zero overall?

The decrease is applied to the already increased amount, so the two percentages use different bases. Starting at 100 gives 120 after the increase and 96 after a 20% decrease.

Can a percentage be greater than 100%?

Yes. A result above 100% simply means the compared amount is larger than the reference amount. For example, 150 is 150% of 100.