Percentage Calculator

A free online tool by Notes Calculator to calculate percentages.

Understanding Percentage Calculations

Calculating percentages is a fundamental mathematical skill that comes up frequently in work, finance, and everyday life. Whether you’re calculating tax, sales, profit margins, discounts, or more, knowing how to work with percentages is essential. Let’s break down the key steps to accurately calculate percentages.

What is a Percentage?

To start, it’s important to understand what a percentage actually represents. A percentage simply expresses a number as a fraction of 100. For example, if something is 20%, it means it is equal to 20/100 or 20 hundredths. Percentages are commonly used to express parts of a whole using a scale of 0-100.

The Basic Percentage Formula

The basic formula for calculating a percentage is:

Percentage = (Part / Whole) x 100

Let’s break this down step-by-step:

Part - This is the number we want to find the percentage of. It represents the portion we are interested in.
Whole - This is the total amount. It is the base that the part is being taken from and calculated as a percentage of.
x 100 - Multiplying the fraction by 100 converts it to a percentage.

For example, if you scored 80 points on a test out of a possible 100 total points, your percentage would be:

(Part / Whole) x 100
(80 / 100) x 100 
0.8 x 100
= 80%

Calculating Percentages of Quantities

Often, we need to calculate an actual numerical value of a percentage, rather than just the percentage amount. For example, calculating sales tax, discounts, or profit margins.

To do this, we take the percentage as a decimal (move the decimal two places left) and multiply it by the original quantity.

For example, if an item costs $100 and sales tax is 9%, the calculation would be:

9% as a decimal is 0.09
0.09 x $100
= $9

So the sales tax on a $100 item at a 9% tax rate is $9.

I hope this blog post explain the key concepts and formulas. Being comfortable working with percentages in a variety of scenarios is an important lifelong mathematical skill.

Free Percentage Calculator tools

Find percentage that a specific value represents out of the total value

For example to calculate how much is 20% of 10:

(20 / 100) x 10
0.2 x 10
= 2

Find what percent is a value of another

For example to calculate what percent is 20 of 50:

20 / (50 / 100)
20 / 0.5
= 40%

Find the sum of a value and a percentage

For example to calculate what values is 200 + 10%

((10 / 100) * 200) + 200
(0.1 * 200) + 200
20 + 200
= 220