Percentages come up constantly — discounts, tax, tips, growth rates, grades, interest — and the different kinds of percentage question are easy to confuse. These are the four that cover nearly everything.
How to use the Percentage Calculator
- Pick the calculation that matches your question
- Enter the two values
- Read the result
- For increases and decreases, check which value is the base
The four calculations
- What is X% of Y? The basic one. 20% of 250 = 50. Used for discounts and tax.
- X is what percent of Y? The reverse. 50 is 20% of 250. Used for shares, completion rates, pass rates.
- Percentage change from X to Y. From 200 to 250 is a 25% increase. Used for growth and comparisons over time.
- Add or remove X%. Adding 20% to 250 gives 300; removing 20% from 300 gives 240 — not 250.
Why a 20% drop does not undo a 20% rise
This asymmetry causes real errors, especially in reporting.
Start at 100. Add 20% → 120. Now remove 20% → 96, not 100. The increase was calculated on 100 and the decrease on 120, so the two percentages are taken from different bases.
The same effect bites harder with losses. An investment that falls 50% needs a 100% gain to recover, because it is climbing back from a smaller base. A 90% fall needs a 900% gain.
The other common error is confusing percent with percentage points. Interest moving from 5% to 7% is a rise of two percentage points, but a 40% increase. Both are correct and they describe very different things.
Frequently asked questions
Why doesn't removing the same percentage get me back to the original?
Because the two percentages are calculated on different bases. Adding 20% to 100 gives 120; removing 20% from 120 removes 24, not 20, leaving 96.
What is the difference between percent and percentage points?
Going from 5% to 7% is a 2 percentage point rise and a 40% increase. Percentage points measure the absolute gap; percent measures relative change.
How do I find the original price before a discount?
Divide, do not subtract. If ₹80 is after a 20% discount, the original is 80 ÷ 0.8 = ₹100. Adding 20% back to 80 would wrongly give 96.
How do I calculate a percentage of a percentage?
Multiply the decimals. 50% of 20% is 0.5 × 0.2 = 0.1, or 10%. This comes up with stacked discounts — two successive 20% discounts total 36%, not 40%.