Percentage Calculator
The three percentage questions people actually ask, each with the formula shown so you can check the working.
How to use it
- Pick the row that matches your question — all three work at the same time.
- Type your numbers. The answer updates as you type; there is no equals button.
- The grey line under each answer shows the formula used, so you can repeat it by hand.
An increase and a decrease do not cancel out
This is the percentage mistake that costs real money, and it catches careful people.
Take 1,000. Add 10 percent and you have 1,100. Now take 10 percent off that, and you do not get back to 1,000 — you get 990. The rise was ten percent of 1,000, but the fall was ten percent of 1,100, and the second number is bigger.
The same trap works in reverse and the gap widens with the numbers. A share that falls 50 percent needs to rise 100 percent to recover. A salary cut of 20 percent needs a 25 percent rise to undo. Use the third box on this page whenever you need the honest answer rather than the intuitive one.
Percent and percentage points are different things
If an interest rate moves from 4 percent to 6 percent, it has risen by two percentage points — and by fifty percent. Both statements are true, and they sound wildly different, which is why the smaller-sounding one appears in announcements and the larger one in headlines.
The rule is simple once you have it. Percentage points are the plain difference between two percentages. Percent is that difference expressed as a share of where you started. When somebody quotes a change in percentages without saying which they mean, it is worth working out both before you react.
Frequently asked questions
How do I calculate a discount?
Use the first row. For 20% off a ₹2,500 item, ask “what is 20% of 2500?” — that gives the ₹500 you save, so you pay ₹2,000.
What is the difference between percentage points and percent?
Going from 10% to 15% is a rise of 5 percentage points, but a 50% increase. Both are correct and they mean different things — the third row gives you the percentage version.
Why can I not work out the change from zero?
Percentage change divides by the starting number, and dividing by zero has no answer. Any growth from zero is infinite in percentage terms.
How do I add tax or GST to a price?
First row: 18% of 1,000 is 180, so the price with 18% GST is 1,180. To strip tax back out of an inclusive price, divide by 1.18 instead.