Percentage Calculator
Three percentage questions, one calculator — and it shows you the working so you can check it or learn it.
Result
What this calculator does
Percentages turn up everywhere: the 15% service charge on a restaurant bill, the 30% off sticker in a shop window, the 4.5% pay rise in your offer letter. They are simple arithmetic, but they are easy to get backwards under time pressure — and getting them backwards can cost real money.
This calculator answers the three percentage questions people actually ask. What is 15% of 250? Forty-five is what percentage of 180? And what happened, in percentage terms, when a number moved from 1,200 to 1,500? Pick a tab, type your numbers, and the answer appears as you type, together with the working so you can see exactly how it was reached.
How to use it
- Choose the tab that matches your question. Most people want the first one, “What is X% of Y?”
- Type the percentage and the number. The result updates while you type — there is no button to hunt for.
- Read the step-by-step working underneath if you want to check the maths or show it to someone else.
- Use Copy to put the answer on your clipboard, or Share to send a link that opens with your numbers already filled in.
The formula
What is X% of Y? result = (X ÷ 100) × Y
X is what percent of Y? result = (X ÷ Y) × 100
Percentage change result = ((new − old) ÷ |old|) × 100
The bars around old mean absolute value, which keeps the sign of the change correct when the starting number is negative.
Worked examples
| Scenario | What you enter | Result |
|---|---|---|
| A 15% tip on a $86 dinner bill | 15% of 86 | $12.90 — so $98.90 in total |
| Scoring 45 out of a possible 180 on a test | 45 is what % of 180 | 25% |
| Rent rising from AED 1,200 to AED 1,500 a month | Change from 1200 to 1500 | A 25% increase |
| 5% VAT on a AED 2,400 invoice | 5% of 2400 | AED 120 tax, AED 2,520 total |
| Shares falling from $92 to $71 | Change from 92 to 71 | A 22.83% decrease |
Frequently asked questions
Divide the percentage by 100, then multiply by the number. For 15% of 250: 15 ÷ 100 = 0.15, and 0.15 × 250 = 37.5. A quick mental shortcut is to find 10% first by moving the decimal point one place left, then build the rest from it — 10% of 250 is 25, half of that is 12.5, so 15% is 37.5.
Percentage change is relative; percentage points are absolute. If an interest rate moves from 4% to 6%, that is a rise of two percentage points, but a 50% increase in the rate itself. News reports mix these up constantly. When you are comparing two percentages, say “percentage points”. When you are comparing two quantities, say “percent”.
Because each percentage is taken from a different base. If 100 drops 50% you have 50. A 50% rise on 50 is only 25, taking you to 75, not back to 100. To recover from a 50% fall you need a 100% gain. This asymmetry is why large losses are so much harder to recover from than they look.
To add 5% VAT, multiply by 1.05. To find the pre-tax price from a tax-inclusive one, divide by 1.05 — do not subtract 5%, which gives the wrong answer. On a AED 105 tax-inclusive price, dividing gives AED 100 net and AED 5 tax; subtracting 5% would have given AED 99.75, which is wrong by 25 fils.
Yes, whenever the part is bigger than the whole you started with. Sales of 250 units against a target of 100 is 250% of target. Percentage increases are unbounded — a price going from $2 to $10 is a 400% increase. Percentage decreases, on the other hand, cannot exceed 100% for a quantity that cannot go below zero.
It shows up to four decimal places and drops trailing zeros, so 25% appears as 25% rather than 25.0000%. The underlying calculation uses full double-precision arithmetic, so nothing is lost before the display step. If you need the unrounded figure, the step-by-step working shows six decimal places at the intermediate stage.
No. Every calculation runs inside your own browser using JavaScript. Nothing you type is transmitted to a server, logged, or shared with a third party. That is also why the calculator keeps working when you lose your connection, and why a shared link carries your numbers in the link itself rather than in a database.
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