Are the values I type sent to a server?
No. Every calculation happens inside your browser and nothing is stored anywhere.
Free Study Tool
Percentage Calculator
Discounts, percent change, VAT and test scores in one place. Results appear as you type, and every one of them comes with the formula behind it.
Nothing you type ever leaves your browser.
Enter a value and the answer appears straight away.
To see how it works, press "Fill in an example" above.
Results
How to use
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1
Pick a calculation type
Choose one of the seven modes — "B% of A", "A is what % of B", "Percent change", "Add or subtract %", "Discount", "VAT" and "Test score" — and only the boxes you need appear.
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2
Type the values
The answer updates as you type. You can write 20,000 or 30% with the comma and the symbol attached; only the digits are read.
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3
Check the result and the formula
Every row shows the expression it came from, so you can tell at a glance whether a number is "the percentage of the value" or "the value with that percentage added".
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4
Copy what you need
The copy button on each row takes a single value; "Copy all results" takes the formulas and the notes as well.
What people use it for
Checking a sale price in a shopping cart, working out how much revenue grew against last month, splitting an invoice into net amount and VAT, converting a marked test into a score — anything where a ratio is involved. It also works well for revising the percentage and ratio topics in school maths.
Because it puts phrases that sound alike but mean different numbers side by side — "30% off" versus "30% added", "a 50% increase" versus "150% of the original" — you can paste the result straight into a message and the other person will follow it.
Frequently asked questions
What is the difference between "30% of 20,000" and "20,000 increased by 30%"?
The first is 6,000 and the second is 26,000. The first is the size of the share; the second is that share added to the original value. This calculator shows both on one screen, each with its formula.
I keep confusing the growth rate with the value after growth.
The "Percent change" mode shows the change and "the new value as a percentage of the old" next to each other. If 20 grows to 30, the increase is 50% and the new value is 150% of the old — two ways of saying the same thing.
If I add 30% and then take 30% off, do I get back to where I started?
No. 20,000 increased by 30% is 26,000, and taking 30% off that gives 18,200. To get back to the original you need to take off about 23.08%, and the calculator tells you that figure.
Can I find the discount rate from just the list price and the sale price?
Yes. In "Discount", fill in the list price and the sale price and the rate appears. It works the other way too: give the rate and the sale price and the list price is worked back.
How do I get the net amount out of a VAT-inclusive total?
Divide the total by 1.1 when the rate is 10%. A total of 11,000 is a net amount of 10,000 plus 1,000 of VAT. In the "VAT" mode, choose "Total → net amount".
Which grade cut-offs are used for test scores?
90, 80, 70 and 60 are used as an example scale. Schools and exams differ, so treat it as a reference. The number of extra correct answers needed to reach the next grade is shown too.
What does "about" in front of a result mean?
It means the value did not divide evenly and has been rounded at the third decimal place. Exact values do not get the word, and the formula uses the ≈ sign to mark it.
Can I type commas or a % sign?
Yes. Write 20,000 or 30% if you like — only the digits are read. Decimal points and minus signs work as you would expect.
Does it work offline?
Once the page has loaded it keeps calculating without a connection, because it never calls an external server.
Can I move the results into a document or a chat?
The copy button on each row takes a single value; "Copy all results" takes the formulas and the notes with it, so whoever reads it can see how the number was reached.