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Percentage Calculator

Calculate percentages, proportions, and percentage increase or decrease. Calculate values directly on your device.

Calculation type

Enter the percent rate.

Enter the base number.

Calculated result
30

15% of 200 is 30.

About this tool

Percentage Calculator solves common everyday percentage problems. You can calculate the percentage of a number, determine what percentage one quantity represents of another, or find the percentage increase or decrease between two values. Calculations update in real time as you type, and everything runs locally on your device with complete privacy.

When to use it

  • Calculate retail discounts, promotional sales margins, and sales tax amounts
  • Determine tips, dining bills, and service fee percentages
  • Compute academic exam scores, assignment percentages, and grade weights
  • Analyze financial growth, revenue changes, inflation metrics, or budget variances
  • Calculate demographic proportions, survey responses, and statistical shares

How to use it

To calculate a percentage

  1. Choose your Calculation type using the options above:
    • Percentage of a number: Enter the percentage rate and total amount (for example: 15% of 200).
    • Proportion as a percentage: Enter the part and total whole (for example: 25 out of 100).
    • Percentage increase or decrease: Enter the initial starting value and final ending value (for example: from 50 to 75).
  2. The calculated result, clear explanation, and copy button update immediately.
  3. Press Copy result to copy the formatted number directly to your clipboard.

Questions

How do I calculate a percentage of a number?

Multiply the number by the percentage fraction (percentage divided by 100). For example, to find 20% of 80:

Result=20100×80=0.20×80=16\text{Result} = \frac{20}{100} \times 80 = 0.20 \times 80 = 16

What is the formula for percentage increase or decrease?

Subtract the original value from the new value, divide by the absolute value of the original value, and multiply by 100:

Percentage Change=(New Value−Original Value∣Original Value∣)×100\text{Percentage Change} = \left(\frac{\text{New Value} - \text{Original Value}}{|\text{Original Value}|}\right) \times 100

A positive result represents an increase (growth), while a negative result indicates a decrease (reduction).

How do I find what percent one number is of another?

Divide the part by the total whole and multiply by 100:

Percentage=(PartTotal)×100\text{Percentage} = \left(\frac{\text{Part}}{\text{Total}}\right) \times 100

For example, if you scored 42 points out of 50 on an exam: (42 / 50) * 100 = 84%.

Does this tool send any numbers to a server?

No. All arithmetic is computed instantly in local JavaScript in your browser memory. No data is stored, tracked, or transmitted across the internet.