Percentage Calculator
Calculate percentages, percentage of a number, and percentage changes
Instant calculations with precise formulas. No complexity, just the results you need.
Formula
(value / total) × 100How to Use Percentage Calculator
- Provide your input values.
- Understand the calculation method shown.
- Get immediate and accurate results.
- Use the output for planning or analysis.
Examples
Example 1
Input
value: 50
total: 200
Output
percentage: 25
Example 2
Input
value: 75
total: 300
Output
percentage: 25
This covers the general case of expressing one number as a percentage of another, which is what sits behind a test score, an occupancy rate, a conversion rate, or any figure you need to compare on a common 0 to 100 scale rather than in raw units.
The formula
percentage = (part / whole) x 100- part
- the smaller quantity you are measuring
- whole
- the total or reference quantity
Worked example
34 of 40 students in a class passed an exam. The percentage is (34 / 40) x 100 = 85%. If the class had instead been 34 out of 45, the same 34 passes would only be (34 / 45) x 100 = 75.6%, a reminder that the percentage tells you nothing about the size of the class on its own, only the proportion within it.
What trips people up
- Part and whole must be measured in the same unit; mixing a count of people with a count of households produces a meaningless ratio.
- A percentage over 100% is valid whenever the part exceeds the whole, such as sales this quarter against last quarter's target.
- Rounding the percentage before using it in further calculations compounds small errors; round only the final answer.
- Zero as the whole makes the calculation undefined, since dividing by zero has no result, which comes up more often than it sounds when a total has not been entered yet.
Frequently asked questions
- Can a percentage be negative?
- Yes, whenever the part being measured represents a loss or a decrease relative to the whole, such as a negative return on an investment expressed as a percentage of the amount invested.
- What is the difference between a percentage and a percentage point?
- A percentage point is a difference between two percentages themselves; moving from 20% to 25% is a 5 percentage point increase, but it is a 25% relative increase in the underlying figure.
- How do I find the whole if I know the part and the percentage?
- Rearrange the formula to whole = part / (percentage / 100); if 34 is 85% of a class, the class size is 34 / 0.85 = 40.
- Why do percentages in a table sometimes not add up to exactly 100%?
- Because each figure was rounded independently before display; the underlying unrounded numbers do sum to 100%, the rounding just introduces small individual gaps.
- Is a percentage always calculated out of 100?
- Yes by definition, that is what 'per cent' means, but the whole it is measured against can be any quantity at all, a headcount, a dollar figure, or a distance.
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