Free · Algebra and geometric models

Equal-Weight and Sample-Weighted Percentages

Average two through ten percentages equally or weight them by their underlying sample sizes.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

For the worked inputs, Average percentage = 30.

Equal mean=Σp/n; weighted mean=Σ(wp)/Σw

Worked example

Enter these known values and leave the other values blank.

Percent #1
20 %
Percent #2
40 %
Average percentage
30 %

Assumptions and limitations

  • Values use a numerical percentage scale: 20 means 20 percent. The arithmetic also permits signed rates or rates above 100 percent.
  • A weighted average requires positive weights and accepts fractional weights, such as exposure amounts. When weights represent literal sample counts, enter whole counts. Equal averaging is appropriate only when the denominators are equal.

Common questions

What must I enter?

Choose the mode when available and enter its independent known quantities. Leave an unknown editable quantity empty to use a supported inverse.

How should I use the result?

Interpret the numbers within the stated mathematical assumptions. Available unit selectors convert quantities; display rounding does not replace the internal calculation.

Can sample weights be fractional?

Yes. This weighted mean accepts any positive weight, including fractional exposure amounts. Use whole counts when a weight represents the number of observations in a literal sample.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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