ToolVaults

Percentage Calculator

Every percentage calculation in one place: X% of Y, X is what % of Y, change from A to B, add/subtract %, add tax. Runs entirely in your browser.

Runs 100% in your browser — nothing is uploaded.
Result
30
15% of 200 = 30
Example: 15% of 200 = 30

How to use

  1. 1
    Pick a mode

    Six modes: % of, is what %, change from A to B, increase by, decrease by, add tax/markup.

  2. 2
    Enter your numbers

    Two inputs per mode. The result updates as you type.

  3. 3
    Share the calc

    Every input is in the URL — copy the address bar to send someone the same calculation.

Examples

20% of 150
Input
Mode: % of · X = 20 · Y = 150
Output
30
Classic tip / discount math.
45 is what % of 180?
Input
Mode: is what % · X = 45 · Y = 180
Output
25%
Inverse of "% of" — figure out the ratio.
Percentage change from 80 to 100
Input
Mode: change · A = 80 · B = 100
Output
+25% (increase of 20)
Positive result = increase, negative = decrease. Handy for year-over-year comparisons.
Add 7% sales tax to $89.99
Input
Mode: add tax · Amount = 89.99 · Rate = 7
Output
$96.29 (tax: $6.30)
Result and the tax portion both shown so you can itemize.

Frequently asked

How do I calculate a percentage increase?

Use "Change from A to B". Enter the original value as A and the new value as B. Positive result = increase, negative = decrease.

What is the difference between "% of" and "is what %"?

"% of" answers "15% of 200 is what?" (result: 30). "Is what %" answers "30 is what % of 200?" (result: 15%). Same numbers, inverse operation.

Can I use this for sales tax or markup?

Yes — use "Add tax / markup" to compute an amount plus a percentage. For gross-to-net (removing tax from a total), use "Decrease by %" with the tax rate.

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