Percentage Calculator
Calculate percentages, percentage change, and percentage of a number instantly.
Mathematical Formula
Overview & Explanation
Percentages are a fundamental mathematical tool representing a fraction of 100. They are widely used in finance, shopping discounts, statistics, and daily calculations.
How It Works
- To find X% of Y: Multiply Y by (X / 100).
- To find what percentage X is of Y: Divide X by Y and multiply by 100.
- To find percentage change: Subtract initial value X from final value Y, divide by initial value X, and multiply by 100.
Practical Applications
- Calculating sales tax or shopping discounts.
- Determining grade percentages in school exams.
- Measuring salary increases or financial growth rates.
The three percentage questions
Almost every percentage problem is one of three types. "What is X percent of Y?" is solved with Y × X / 100. "X is what percent of Y?" is solved with X / Y × 100. "X is P percent of what number?" is solved with X × 100 / P. Identify which question you are asking first, and the right formula follows.
A percentage is just a fraction with 100 as the denominator: 18 percent means 18 out of every 100, or 0.18.
Worked examples
GST of 18 percent on a 2,400 bill is 2,400 × 18 / 100 = 432. If you scored 42 out of 60 in a test, your score is 42 / 60 × 100 = 70 percent. If 15 percent of your salary is 9,000, your salary is 9,000 × 100 / 15 = 60,000.
Common mistakes
Percentage points and percent are not the same: a rate rising from 6 percent to 8 percent is a 2 percentage-point rise but a 33 percent increase. Also, increases and decreases do not cancel out: a price that rises 20 percent and then falls 20 percent ends 4 percent lower than it started, because the fall is applied to a bigger number.
Worked Example: Finding 17% of 850
Calculate 17% of 850 step by step.
Convert percentage to decimal
17 / 100
Multiply decimal by value Y
0.17 * 850
Frequently Asked Questions
How do I calculate percentage of a number?
What is the formula for percentage increase?
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