When to use this calculator
A simple average of two percentages can be misleading when one group is larger. Weight by each denominator to combine them.
Explore the percentage & ratio calculators for other questions in this topic. For a related calculation, use the What Percent Calculator: Find what percentage one amount represents of another.
PUTTING IT INTO PRACTICE
Weighted Percentage: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| First group rate (%) | 50 |
| First group size (integer) | 20 |
| Second group rate (%) | 80 |
| Second group size (integer) | 30 |
| Result | 68 % |
- Check the input labels and enter the example values above.
- Apply the relationship: Combined rate = (first rate × first size + second rate × second size) ÷ total size.
- The result is 68 %, rounded for display.
How to interpret your result
Rates should refer to the same outcome. Rounded input rates can produce an approximate pooled result.
Choose the base before calculating. Percentage points compare two rates by subtraction, while percentage change divides a difference by an original value. Successive discounts apply one after another rather than adding together.
Frequently asked questions
Should I use percentage change or percentage points?
Use percentage change for relative movement from a baseline. Use percentage points for the direct difference between two percentage rates.
When is the weighted percentage calculator useful?
A simple average of two percentages can be misleading when one group is larger. Weight by each denominator to combine them.
How do I use the weighted percentage calculator?
Enter first group rate (%), first group size (integer), second group rate (%), second group size (integer). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Combined rate = (first rate × first size + second rate × second size) ÷ total size.
What should I check before using the result?
Rates should refer to the same outcome. Rounded input rates can produce an approximate pooled result.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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