🧮 Calculators

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).

📘 Related NCERT chapter: Comparing Quantities (Class 7)