Calculateos

Percentage Calculator

Free online percent calculator for discounts, tips, tax, and grade math. Example: What is 20% of 80? Answer: 16.

What is X% of Y?

%

of

Result

30

What is

% of

?

30

X is what percent of Y?

of

is what % of

?

X is Y% of what?

is

is

%

% of what?

Increase or decrease between two numbers

Find the percentage increase or decrease between two values.

Increase of 25%
+25%

How to Calculate Percentage

A percentage expresses a part per hundred. To find what is X% of Y, multiply Y by X and divide by 100, or multiply Y by the decimal form of the percent. This is the most common percentage calculator task for shopping, tax, and budgeting.

To compare two numbers as a percent, divide the part by the whole and multiply by 100. For percentage change, subtract the old value from the new value, divide by the old value, and multiply by 100. Positive results mean an increase; negative results mean a decrease.

Pick the matching calculator above, enter your numbers, and press Calculate.

Common Percentage Calculations

Percentages power everyday decisions: store discounts, restaurant tips, course grades, sales tax, and simple interest estimates. The four calculators above cover percent of, what percent, percent of what, and percentage change. We are also building discount, tip, BMI, age, time, and GPA calculators—coming soon on Calculateos.

Why Use Our Percentage Calculator?

Calculateos is a simple percentage calculator built for speed on mobile and desktop: large inputs, clear labels, instant results, and no signup. Use it as an easy percentage calculator for homework, shopping, and quick workplace checks.

Want to understand the math behind the answers? Review the formula cards below or open our percentage guide from the links at the end of this page.

Percentage Change Calculator

Find the percentage increase or decrease between two values.

Increase of 25%
+25%

Percentage Calculator Formulas

Core percentage formulas with worked examples for everyday math.

Formula 1: What is X% of Y?

Result = (P / 100) × N

Example: 20% of 150 = (20/100) × 150 = 30

Formula 2: X is what percent of Y?

Result = (X / Y) × 100

Example: 45 out of 180 = (45/180) × 100 = 25%

Formula 3: X is Y% of what?

Result = X / (Y / 100)

Example: 30 is 20% of what = 30 / (20/100) = 150

Formula 4: Percentage increase/decrease

Δ% = ((B - A) / A) × 100

Example: From 80 to 100 = ((100-80)/80) × 100 = +25%

Frequently Asked Questions

How to calculate percentage of a number?

To calculate a percentage of a number, multiply the number by the percent divided by 100. Example: 20% of 80 = 80 × 0.20 = 16.

What is the formula for percentage change?

Percentage change = [(New Value - Old Value) ÷ Old Value] × 100. A positive result means increase; negative means decrease.

How to find percentage between two numbers?

Divide the first number by the second number, then multiply by 100. Example: 20 ÷ 80 × 100 = 25%.

What is 15% of 80?

15% of 80 = 12. Example: 80 × 0.15 = 12.

What is 20% of 100?

20% of 100 = 20. Example: 100 × 0.20 = 20.

Can I use this percentage calculator on mobile?

Yes. Our percentage calculator works on mobile, tablet, and desktop, with large input fields that are easy to use on any device.

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