Free Percentage Calculator: Find Percentages Instantly

Free percentage calculator with 3 tools: find what percent of a number is, what percentage one number is of another, and add a percentage to a value.

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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.

These are the key concepts and formulas for percentage calculations. Being comfortable working with percentages in a variety of scenarios is an important lifelong mathematical skill.

Percentages come up in many areas: use our discount calculator for shopping deals, the tip calculator for restaurant bills, or the profit margin calculator for business pricing.

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 value is 200 + 10%:

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

Frequently Asked Questions

How do I calculate a percentage of a number?

Divide the percentage by 100 to convert it to a decimal, then multiply by the number. For example, 25% of 200: divide 25 by 100 to get 0.25, then multiply 0.25 by 200 to get 50.

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

Divide the part by the whole, then multiply by 100. For example, to find what percentage 30 is of 120: (30 / 120) x 100 = 25%.

How do I add a percentage to a number?

Multiply the number by (1 + percentage/100). For example, 200 + 10%: 200 x 1.10 = 220. Or calculate the percentage amount first (200 x 0.10 = 20) and add it to the original (200 + 20 = 220).

Percentage Calculations in Notes Calculator

Notes Calculator supports a full range of natural percentage expressions — no formulas needed:

// Percentage of a number
25% of 200

// Add or subtract a percentage
200 + 10%
200 - 15%

// Percentage on / off
10% on 200
10% off 200

// Reverse: what was the original?
180 is what % off 200

// Percent change
50 to 75 as %

You can also use 15% of bill with variables, chain percentages like price - 20% + 8% (discount then tax), and use previous to reference the last result. Learn more about how notepad calculators compare to spreadsheets for everyday math.