Free percentage calculator for all your needs. Calculate percentages, percentage change, increase/decrease, and more. Easy to use with step-by-step formulas.
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Ce calculateur fournit des estimations à titre informatif uniquement. Consultez un professionnel financier qualifié.
The Three Percentage Calculations You Use Every Day
Nearly every percentage question falls into one of three types: (1) What is X% of Y? (e.g., what is 15% of $85?). (2) X is what percent of Y? (e.g., 45 correct out of 60 questions = what percent?). (3) What is the percentage change from X to Y? (e.g., price went from $80 to $96 — what percent increase?). Mastering these three formulas covers discounts, exam scores, pay raises, investment returns, and any other percentage calculation you encounter.
Three Percentage Formulas with Examples
(1) X% of Y: multiply Y by X/100. What is 15% of $85? 85 × 0.15 = $12.75. (2) X is what percent of Y: (X/Y) × 100. 45 out of 60 = (45/60) × 100 = 75%. (3) Percentage change: ((New − Old) / Old) × 100. From $80 to $96 = ((96−80)/80) × 100 = 20% increase. Select the calculation type in the calculator above, enter your numbers, and see the result with the formula shown.
Frequently Asked Questions
(Part / Whole) × 100 = Percentage. Example: 36 out of 90 = (36/90) × 100 = 40%. This is the most common percentage calculation — exam scores, survey results, completion rates.
((New Value − Old Value) / Old Value) × 100. From $80 to $100: ((100−80)/80) × 100 = 25% increase. From $100 to $80: ((80−100)/100) × 100 = −20% (a 20% decrease).
Percentage points are the arithmetic difference between two percentages. Percent change is the relative change. If approval rating rises from 40% to 50%: it rose 10 percentage points, but increased by 25% in relative terms (10/40 × 100 = 25%). These are very different numbers — a key distinction in political reporting.
For 20% tip: move decimal left one place to find 10%, double it. On $65: 10% = $6.50, double = $13.00 for 20% tip. For 15%: find 10% ($6.50), halve it ($3.25), add together = $9.75. For 18%: use the calculator — it is not clean mental math.
