Percent

Percentage Calculator

Details

How to use Percentage Calculator

What the tool does, how to run it, and what to expect from the result.

How to calculate a percentage of a number

The calculator takes two numbers: a percent and a value. It multiplies the value by the percent divided by 100 and shows the result as you type, with no submit step.

Both fields accept decimals. They do not accept commas, currency symbols, or percent signs, and any of those characters cause the field to be read as zero.

  • Type the percentage into the Percent (%) field. It starts at 15.
  • Type the number you are taking that percentage of into the Of value field. It starts at 200.
  • Read the first result line, labelled with your two inputs, for example 15% of 200 = 30.
  • Change either field and the result updates immediately, so you can sweep a range of percentages without re-entering the base.

The percentage formula, in all three directions

Every percentage question is one formula rearranged. Part = percent / 100 x whole answers "what is 15% of 200" (30). Percent = part / whole x 100 answers "what percent is 30 of 200" (15%). Whole = part / (percent / 100) answers "30 is 15% of what" (200). The calculator computes the first two directly: the headline line and the Compare line.

The third direction, recovering the whole, is the one the tool does not automate. Divide the part by the percent as a decimal: 30 / 0.15 = 200. It is also the correct way to undo a percentage that was already applied, which trips people up because subtracting the same percent does not undo adding it.

Add or subtract a percentage: tax, tips, and discounts

The third and fourth result lines show the value with the percentage added and subtracted, which covers the everyday cases in one glance: 200 plus 15% is 230, and 200 minus 15% is 170. That is a sales-tax total, a tipped bill, or a discounted price without a separate calculator.

For a purpose-built version of those jobs with their own fields, the Discount Calculator handles price and percent off, and the Tip Calculator splits a tipped bill between people. This page is the general-purpose one: two numbers in, all four readings out.

Tips

Getting a better result out of Percentage Calculator

Specific settings and thresholds, not general advice.

  • The first result line is percent / 100 x value. The defaults, 15 and 200, give 30. There is no calculate button, the number re-renders on every keystroke.
  • The Compare field answers the other question people come here for: what percent one number is of another. Enter 50 against a value of 200 and it reads 25 percent.
  • To answer what percent is 30 of 200, divide directly: 30 / 200 x 100 = 15. Then put 15 in the percent field and confirm the tool returns 30.
  • Percentages commute, which is a fast mental shortcut: 18% of 50 is the same as 50% of 18, which is 9. Swap the two fields whenever one order is easier to reason about.
  • Inputs are parsed with Number(), so 1,000 and $1,000 both fail to parse and are treated as 0. Type digits and a decimal point only.
Limits

What Percentage Calculator does not do

The honest boundary, so you do not lose time finding it yourself.

  • It works on one pair of numbers at a time, with no history and no batch mode.
  • No reverse percentage, so it cannot find the original number before a percentage was added or removed.
  • No chaining. For a from-value to to-value comparison use the Percentage Change Calculator.
  • No copy button, no history, and no shareable link. A refresh resets both fields to 15 and 200.
Reference

Terms used on this page

Short, plain-language definitions for the formats and settings above.

At a glance

Who Percentage Calculator is for

A quick way to understand who this helps, what it solves, and where it connects next.

Best fit

Shoppers, students, freelancers, and anyone who needs a quick, private calculation.

Ideal for

Fast everyday math without a spreadsheet, app install, or sign-up.

FAQ

Common questions

Short answers for the questions people usually have before trying a utility like this.

How do I work out what X percent of Y is?

Type the percent in the first field and the number in the second, and read the first result line. The formula behind it is percent divided by 100, times the value: 15% of 200 is 0.15 x 200 = 30.

Is this percentage calculator free?

Yes, free with no signup. It recalculates on every keystroke, so there is not even a button to press.

What is 20% of 150?

30. Twenty percent is one fifth, so divide by 5. The calculator confirms it: enter 20 and 150 and the first line reads 30, with 150 plus 20% (180) and minus 20% (120) below it.

Can it tell me what percent one number is of another?

Yes, that is what the Compare field is for. With a value of 200 and a compare figure of 50, it reads 25 percent. The tool also shows the value with the percentage added and subtracted, which is the other common reason people open a percentage calculator.

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

Divide the part by the whole and multiply by 100. For 30 out of 200 that is 30 / 200 x 100 = 15%. You can verify it here by entering 15 as the percent and 200 as the value, which returns 30.

Why does typing 1,000 give me 0?

The field is parsed with JavaScript's Number(), which rejects thousands separators and currency symbols. A comma turns the whole entry into NaN, and the tool falls back to 0. Enter 1000 with no comma.

Is 15% of 200 the same as 200% of 15?

Yes, both are 30. Multiplication is commutative, so you can swap the two fields whenever the reversed version is easier to do in your head. It is the reason 18% of 50 is best computed as 50% of 18.

How do I reverse a percentage, for example find the price before 20% was added?

Divide by 1 plus the percentage as a decimal. A total of 120 that already includes a 20% addition came from 120 / 1.2 = 100. This tool only works forward, so do that division yourself.

Does any number I type reach a server?

No. The entire calculation is a few lines of arithmetic running in your browser tab. Nothing is sent anywhere, and the tool keeps working with the network disconnected.

How do I calculate the percentage increase between two numbers?

That is a different formula: the change divided by the starting value, times 100. Going from 80 to 100 is a 25% increase. Use the Percentage Change Calculator for that job; this page computes percentages of a single value.

How do I take a percentage off a price?

Enter the discount percent and the price, and read the minus line: 200 minus 15% is 170. Equivalently, multiply the price by 1 minus the percent as a decimal, 200 x 0.85. For a version with dedicated price and savings fields, use the Discount Calculator.

Recommendations

You Might Also Like

Nearby tools from the catalog that fit the same job or workflow.

Cleanor app

Do it all on your device

Cleanor puts these tools in one app: compress and convert images, video, and audio, work with PDFs, and scan text right on your device. Plus free up storage and clear inbox clutter with Email Cleaner. Start with a free trial.

  • iPhone
  • Android
  • Macsoon
  • Windowssoon