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ToolBoxGenie

Percentage Calculator

Calculators · Added 3 July 2026

Percentages trip people up because the same word covers several different operations. This calculator separates them into five clearly labelled modes so you always know which question you are answering.

What do you want to work out?

What is X% of Y?

How to use the percentage calculator

  1. 1Choose the mode that matches your question — for example 'What is X% of Y?'.
  2. 2Fill in the two numbers. The result appears immediately.
  3. 3Read the working shown under the answer to check the method.
  4. 4Switch modes at any time; each mode keeps its own inputs.

Examples

A tip on a restaurant bill

Input
What is 15% of 2,480?
Result
372

Percentage change in traffic

Input
From 12,400 visits to 15,996 visits
Result
+29% increase

Reverse percentage

Input
1,180 is 118% of what?
Result
1,000 — the pre-tax price

About the percentage calculator

The five questions people actually ask

Almost every real percentage problem is one of five shapes. What is X% of Y — the tip, the commission, the tax. X is what percent of Y — the pass rate, the market share, the conversion rate. What is X increased or decreased by Y% — the pay rise, the markdown. What is the percentage change from X to Y — the growth figure in a report. And the reverse: X is Y% of what number — stripping tax back out of a gross total.

Mixing these up is the single most common arithmetic error in business documents. A markup and a margin, for instance, are not the same: a product bought for 100 and sold for 150 carries a 50% markup but only a 33.3% margin.

A shortcut worth remembering

X% of Y always equals Y% of X. That symmetry turns awkward sums into easy ones: 18% of 50 is hard to do in your head, but 50% of 18 is obviously 9. Similarly, 4% of 75 becomes 75% of 4, which is 3.

For rough mental estimates, 10% is a decimal shift and 1% is two. Most everyday percentages can be assembled from those two building blocks — 35% is three tens plus five ones.

Frequently asked questions

What is the difference between percentage change and percentage points?
If an interest rate moves from 4% to 6%, that is a rise of 2 percentage points but a 50% increase. Reports that mix the two are a common source of misleading statistics — percentage points compare two percentages directly, percentage change compares them proportionally.
Why isn't a 20% decrease undone by a 20% increase?
Because each percentage is applied to a different base. Take 100, cut it by 20% and you get 80. Add 20% to 80 and you get 96, not 100. Reversing a 20% cut requires a 25% rise. The reverse-percentage mode handles this for you.
How do I remove a percentage that has already been added?
Divide rather than subtract. To strip 18% tax from a total of 1,180, divide by 1.18 to get 1,000. Subtracting 18% of 1,180 would wrongly give 967.60.

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