- What it does
- The Percentage Calculator answers three related questions from the same two numbers, A and B: what A percent of B is, how much B has changed from A (as a percentage), and what percentage A is of B. Most "percentage calculator" searches are really one of these three questions in disguise, so this tool covers all of them at once instead of making you find three separate calculators.
- When to use it
- Working out a discount, checking how much a price or a score has gone up or down, splitting a bill, or answering any homework question phrased as "what percent...". It works the same regardless of what the numbers represent — money, marks, population, anything.
- Required inputs
- Two numbers: Value A and Value B. Either can be positive, negative, or a decimal.
- Step by step
- 1) Enter Value A. 2) Enter Value B. 3) Press Calculate — all three results appear together: A% of B, the percentage change from A to B, and "B is what % of A".
- Understanding the result
- The three result lines look similar but answer different questions, so read the label before the number. "A% of B" and "B is what % of A" are not interchangeable — they answer opposite questions and usually give very different answers.
- Common mistakes
- Mixing up A and B is the single most common error here. "25 is what % of 200" gives 12.5%, but flip the order and "200 is what % of 25" gives 800% — a very different (and often obviously wrong-looking) answer. If your result looks unreasonable, check which number you put where before assuming the calculator is wrong.
- Example
- A jacket's price drops from 200 to 150. Enter 200 as Value A and 150 as Value B: the percentage-change line shows −25%, meaning the price fell by a quarter.
- Quick tip
- For a plain discount or markup question, put the original value in A and the new value in B, then read only the "percentage change" line — it already accounts for the direction of the change (a fall shows as negative, a rise as positive).
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