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Free Average Percentage Calculator

Average a list of percentages, with optional weighting by sample size or entry weight.

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Averaging percentages isn't always as simple as adding them up and dividing — if the percentages come from groups of different sizes, a simple average can be misleading. This tool averages a list of percentages, optionally weighting each by a sample size or importance weight.

How it works

Without weights, this is a simple mean: add up the percentages and divide by how many there are. With weights, each percentage is multiplied by its weight first, those products are summed, and the total is divided by the sum of the weights — giving groups with larger weights more influence on the result.

  1. Enter percentage 1.
  2. Enter weight 1 (optional).
  3. Enter percentage 2 (optional).
  4. Enter weight 2 (optional).
  5. Enter percentage 3 (optional).
  6. Enter weight 3 (optional).
  7. Enter percentage 4 (optional).
  8. Enter weight 4 (optional).
  9. Enter percentage 5 (optional).
  10. Enter weight 5 (optional).
  11. Click Calculate to see your results.

Examples

Combining pass rates from two class sizes

Class A: 80% pass rate (30 students). Class B: 90% pass rate (10 students). A simple average gives 85%, but the weighted average (accounting for class size) gives 82.5% — closer to Class A since it has three times as many students.

Who should use it

  • Combining survey or test pass-rate percentages across groups of different sizes.
  • Averaging conversion rates across marketing campaigns with different traffic volumes.

Industry applications

  • Education (combining class or cohort pass rates)
  • Marketing analytics
  • Quality control and survey analysis

Advantages

  • Supports both simple and weighted averaging in one tool.
  • Clearly explains which method was used and why.

Limitations

  • Requires consistent weight data for every entry if you choose to weight the average.

Common mistakes to avoid

  • Simply averaging percentages from very different sample sizes without weighting, which overstates the influence of small groups.

Best practices

  • Use sample size (number of respondents, students, transactions, etc.) as the weight whenever group sizes differ meaningfully.

Tips

  • If unsure whether to weight, ask whether the groups being averaged are roughly the same size — if not, weighting usually gives a more representative answer.

Frequently asked questions

Weight them whenever the percentages come from groups of different sizes and you want the overall average to reflect each group's actual contribution, rather than treating every group equally regardless of size.
This tool requires either no weights at all (simple average) or a weight for every entry — mixing weighted and unweighted entries would produce a misleading result, so it asks you to supply all weights or none.

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