Three ways to calculate percentages. Pick a mode and get your answer instantly.
A percentage represents a fraction of 100. The word itself comes from the Latin "per centum," meaning "by the hundred." Percentages are everywhere in daily life: sales tax, discounts, tips, grades, interest rates, and statistics all rely on percentage calculations.
There are three fundamental percentage operations that cover virtually every scenario you will encounter:
This is the most common percentage calculation. You are answering the question "What is X% of Y?" The formula is:
For example, to find 15% of $80: divide 15 by 100 to get 0.15, then multiply by 80 to get $12. This is how you calculate sales tax, tips, discounts, and commissions.
Percentage change tells you how much a value has increased or decreased relative to its starting point. The formula is:
If your rent went from $1,200 to $1,350, the change is (($1,350 - $1,200) / $1,200) x 100 = 12.5% increase. A negative result indicates a decrease. This calculation is essential for tracking investment returns, salary changes, inflation, and performance metrics.
This answers the question "What percentage is one number of another?" The formula is:
If you scored 42 out of 50 on a test, the percentage is (42 / 50) x 100 = 84%. This is how grades, completion rates, and proportions are calculated.