Three different questions get called "percentage", and mixing them up is how a 20% discount followed by a 20% rise fails to return you to where you started.
What the Percentage Calculator does
Handles the three percentage questions people actually ask: what is A% of B, A is what percent of B, and what is the percentage change from A to B.
The third is the one that catches people. Percentage change is always measured against the starting value, so the same absolute movement gives different percentages depending on which direction you travel.
Open the Percentage Calculator and follow the settings and checks below.
The three modes
| Setting | What it means |
|---|---|
| A% of B | A tip, a tax, a discount amount |
| A is what % of B | A share of a total — 30 out of 200 is 15% |
| % change from A to B | Growth or decline, measured against the start |
| Change formula | (B − A) ÷ A × 100 |
| Asymmetry | A 50% fall needs a 100% rise to undo it |
| Percentage vs percentage point | 5% to 6% is a 1 point rise, and a 20% increase |
How to use it
- Pick which of the three questions you are asking — this is the step that matters.
- Enter the two values.
- Read the result.
Practical advice
Percentage changes do not cancel out. A price cut by 20% then raised by 20% ends up 4% below where it started, because the rise is calculated on the smaller number. The same arithmetic explains why an investment that falls 50% needs to double to break even.
Common questions
Why does a 20% cut then a 20% rise not return to the original?
Because each percentage is applied to a different base. Twenty percent off 100 is 80; twenty percent of 80 is only 16, so you come back to 96. The second percentage is measured against the reduced figure.
What is the difference between percent and percentage point?
A rate moving from 5% to 6% has risen by one percentage point, and by 20 percent. Both are correct and they describe the same move — which is exactly why the distinction gets exploited in headlines.
How do I calculate a discount plus tax?
Apply them in the order they actually happen: discount first, then tax on the reduced price. The Discount Calculator does both in one step, including a second coupon.
Can percentage change be over 100%?
Yes, whenever something more than doubles — a rise from 10 to 25 is a 150% increase. A decrease cannot exceed 100%, because that would mean ending below zero.
Useful next tools
- Discount Calculator — Final sale price and total savings, with stacked coupons and tax.
- Tip & Bill Split — Split a bill with tip across any number of people.
- Profit Margin — Margin, markup and selling price from cost.
- VAT / GST Calculator — Add or remove sales tax from any price.
- Simple Interest Calculator — Interest and total value from principal, rate and time.
- Compound Interest — Grow savings with regular contributions over time.
Vootkit provides a browser calculator and educational guidance. Results depend on the values and units you enter, so verify important financial, academic, safety or professional decisions with an appropriate authoritative source.
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