Percentage Calculator

Find a percent of a number, what percent one number is of another, or the change between two numbers.

Enter the values and press Calculate.

Your result will show here.

About this calculator

A percentage is a fraction written out of 100. The mistakes usually come from mixing up which number is the part and which is the whole, or from adding two discounts instead of applying them one after the other.

“What is 18% of 2,500?” multiplies 2,500 by 0.18. “450 is what percent of 2,500?” divides 450 by 2,500. They are different questions. The menu at the top of the form keeps them apart.

Percent change uses the starting number as the base. Going from 80 to 100 is a 25% rise. Going from 100 back to 80 is a 20% fall. The same gap is a different percent because the base changed.

For a shop price with GST after a discount, use the discount calculator. For marks and CGPA, use the CGPA page and the multiplier your board actually printed.

Percentage formulas

A% of B = B × A / 100
A is what % of B = A / B × 100
Change from A to B = (B − A) / A × 100
Increase A by B% = A × (1 + B / 100)
Decrease A by B% = A × (1 − B / 100)

Example

18% of 2,500 is 450.

A change from 80 to 100 is an increase of 25%, because the increase of 20 is a quarter of the starting 80.

18% of 2,500

Direct multiplication.

450

How to use

Choose the question you want answered.
Enter the first number and the second number as the labels describe.
Press Calculate and read the sentence under the result.

Important notes

Percent change needs a starting number that is not zero.
“What percent” needs a total that is not zero.
Two discounts in a shop are successive, not added. Use the discount calculator for that.

FAQ

What is the difference between the first two options?

“A% of B” applies a percent to a number. “A is what percent of B” asks how large A is compared with B.

Why is a fall from 100 to 80 not 25%?

The base is 100, and 20 out of 100 is 20%. The 25% figure is the rise from 80 to 100, where the base is 80.

Can I use decimals?

Yes. The boxes accept decimals.

How do successive discounts work?

Apply the second discount to the price that remains after the first. Use the discount calculator, which does that and can add GST afterwards.

Disclaimer

Results are estimates for general information. Verify important decisions with an appropriate professional or official source.

Last updated 5 October 2026.

Related