Percentage Calculator

Percentage Calculator
Every version of the question, all on the page at once. Type into any line and its answer moves with you.
Percent of a number
ofis
45,000
300,000 × 15 ÷ 100 = 45,000
One number as a percentage of another
is what percent of?
15%
45 ÷ 300 × 100 = 15%
Percentage change
Fromtois a change of
+25%
(150,000 − 120,000) ÷ 120,000 × 100
A difference of 30,000, up.
Increase or decrease by a percentage
byis
330,000
300,000 + 30,000 = 330,000
Discount
withoff costs
62,300
89,000 − 26,700 = 62,300
You save 26,700, and pay 70% of the original price.
VAT and sales tax
with tax—
110,000
100,000 + 10,000 = 110,000
Tax added: 10,000
The whole, from a part
isof
300,000
45,000 ÷ 15 × 100 = 300,000

Percentages are confusing not because the arithmetic is hard but because seven different questions all go by the same word. Finding 15% of 30,000, working out that 45 is 15% of 300, and pulling the tax back out of a VAT-inclusive 110,000 are a multiplication and two divisions — and all three are "a percentage question". This page writes each of those questions out as a sentence and leaves the numbers blank. Find the sentence you would have said out loud, and fill it in.

Percentages go wrong in predictable places. A price cut by 20% and then raised by 20% does not come back to where it started. VAT in Korea is 10% of the supply value, so recovering the supply value from a VAT-inclusive price means dividing by 1.1, not subtracting 10%. And "increased by 50 percentage points" is not "increased by 50%".

Each of those is a separate mode here rather than a single box you have to interpret, so the arithmetic matches the question you were asked.

How to use Percentage Calculator

  1. Read down the seven lines and find the one that matches your question. There are no tabs, so reading is the same as choosing.
  2. Type into the boxes in the sentence. The answer on the right updates as you type, and the other lines are untouched.
  3. Under each answer is the working. Ignore it if you only need the number; quote it if the number is going into a report.
  4. The increase/decrease line and the VAT line have a direction switch. It matters most on VAT, where adding and removing tax are genuinely different sums.
  5. The copy icon puts the raw number on the clipboard — no thousands separators — so it pastes cleanly into a spreadsheet.
  6. Your inputs are remembered in this browser and are never sent anywhere.

Tips & gotchas

  • Taking 30% off and then adding 30% back does not return you to the start. 10,000 less 30% is 7,000, and 7,000 plus 30% is 9,100, because the second percentage is of a smaller number.
  • Removing VAT is dividing by 1.1, not subtracting 10%. From 11,000, subtracting 10% gives 9,900, but the actual pre-tax figure is 10,000. Choosing "back out" on the VAT line does the division.
  • Percent and percentage point are different. A share going from 20% to 25% has risen 5 points, which is a 25% increase. The change line calculates the latter.
  • The denominator of a percentage change is always the starting value. 120 to 150 is a 25% rise, but 150 to 120 is a 20% fall — the same gap of 30, two different percentages.
  • If you know the list price and the sale price but not the discount, use the "percentage of another" line: sale divided by list gives the share you pay, and 100 minus that is the discount.
  • Negative numbers are accepted. Where the starting value is negative — a loss turning into a profit — the sign of a percentage change stops being intuitive, so read the absolute difference alongside it.

Frequently asked questions

Why is the pre-tax amount of a 110,000 total 100,000 and not 99,000?

Because the tax is a percentage of the pre-tax figure, not of the total. If the net is 1, the gross is 1.1, so going back the other way is a division: 110,000 ÷ 1.1 = 100,000, with 10,000 of tax. Subtracting 10% of the gross gives 99,000, a number that appears on no invoice anywhere. It is the single most common mistake in reading a tax receipt backwards.

A rate went from 20% to 25%. Is that a 5% rise?

It is a rise of 5 percentage points, and a 25% increase. Both are correct and they mean different things. When the value itself is a percentage, express the gap in points; when you want the size of the change as a proportion, it is (25 − 20) ÷ 20 × 100 = 25%. It is the same distinction that makes "rates rose 0.25%" and "rates rose 0.25 points" two different news stories.

I know the original and sale price but not the discount

Use the "one number as a percentage of another" line with the sale price first and the list price second. 62,300 against 89,000 gives 70%, so the discount is 30%. The discount line reports the same thing from the other direction — it tells you what share of the original you are paying.

How do stacked discounts work?

Feed the result back into the first box. 20% off followed by a further 10% off is not 30% off, it is 28%: 10,000 becomes 8,000 and then 7,200. That gap is why stacking coupons always feels like less than the numbers promised.

How is rounding handled?

Ratios show two decimal places and general results four. Only the money lines — discount and VAT — round to the whole unit, because a price with four decimals is not a price. What the copy button gives you is the unrounded value, so pasting a chain of results into a spreadsheet does not accumulate error.

Where do my numbers go?

Nowhere. Everything is calculated in the browser and nothing is sent to a server. Your last inputs are kept in this browser’s local storage so the page looks familiar when you come back, and that copy never leaves the device either. Clearing site data removes it.

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