Percentage Calculator — Free Online Percentage Calculator | Fermor

What is a Percentage?

A percentage is a way of expressing a number as a fraction of 100. The word comes from the Latin "per centum", meaning "by the hundred". Percentages are used everywhere — from calculating discounts and taxes to expressing interest rates and statistical data. For example, 45% means 45 out of every 100, or 45/100.

How this percentage calculator helps you

This calculator handles five common percentage scenarios at once. No clicking between modes — just adjust the sliders and see all results instantly.

•Find what a percentage of a number equals (e.g., 15% of 200)

•Determine what percent one number is of another (e.g., 30 is what % of 200)

•Find the whole when you know a part and its percentage (e.g., 30 is 15% of what?)

•Calculate the result of a percentage increase (e.g., what is 200 + 25%?)

•Reverse-calculate the original value after a percentage increase (e.g., 250 is 25% more than what?)

Percentage formula

The fundamental percentage formula is:

Percentage = (Part / Whole) × 100

From this basic formula, you can derive all other percentage calculations. To find a percentage of a number: (Percentage × Number) / 100. To find the whole: Part / (Percentage / 100). For percentage increase: New Value = Original × (1 + Percentage/100).

Frequently asked questions

To calculate X% of Y, multiply Y by X and divide by 100. For example, 15% of 200 = (15 × 200) / 100 = 30. The formula is: Result = (Percentage × Number) / 100.