Percentage Calculator
Three everyday percentage calculations in one place: “what is X% of Y”, “X is what % of Y”, and percent increase or decrease.
How to use it
Pick the question you are asking. “What is 15% of 200?” is the classic tip and discount question (answer: 30). “45 is what percent of 180?” converts a score or part into a percentage (25%). “From 80 to 100” measures change — a 25% increase. The calculator shows the answer and the formula so you can reuse it anywhere.
The one formula behind all three
percentage = (part ÷ whole) × 100 — and percent change = ((new − old) ÷ old) × 100.
Nearly every percentage question in money, school and news headlines is one of these two rearrangements.
Frequently Asked Questions
How do I calculate a discount price?
Use mode 1 to find the discount amount (e.g. 20% of $60 = $12), then subtract it: $48. Or multiply the price by (1 − 0.20) directly.
Why is a 50% loss not undone by a 50% gain?
Percentages are relative to different bases: $100 → $50 is −50%, but $50 → $100 needs +100%. The change mode shows this clearly.
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