Percentage calculations show up everywhere — working out a discount at checkout, calculating a tip, figuring out exam marks, or comparing how much a value has grown or shrunk — but the three common types of percentage question each need a slightly different formula, which is easy to mix up. This calculator covers all three in one place: finding X% of a number, finding what percentage one number is of another, and finding the percentage increase or decrease between two values.
Just pick the calculation mode that matches your question, plug in the numbers, and get an instant, accurate result without having to remember which way round the formula goes.
X% of Y: Result = (X / 100) × Y
X is what % of Y: Result = (X / Y) × 100
Percentage change from A to B: Result = ((B − A) / A) × 100 — positive means an increase, negative means a decrease.
Use 'X% of Y' with the discount rate as X and the original price as Y to find the discount amount, then subtract it from the original price. Or use 'Percentage change' between the original and discounted price to find the discount rate itself.
Because each is calculated relative to a different starting value. A 50% increase from 100 takes you to 150, but a 50% decrease from 150 only takes you back to 75, not 100 — because the decrease is calculated on the larger number (150), not the original 100.
Yes — run one percentage calculation, then feed that result into a second calculation as the new base number. For example, to find 10% of 20% of 500, first find 20% of 500, then find 10% of that result.