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Bonferroni Correction Calculator

Work out bonferroni correction instantly with clear inputs, formula shown and shareable results.

About Bonferroni Correction Calculator

Running m tests at level α inflates the chance of at least one false positive to roughly 1 − (1 − α)^m. The Bonferroni correction divides α by m, which controls the family-wise error rate at the cost of power.

Formula

Bonferroni correction

α_adjusted = α / m, or equivalently compare m·p against α

Worked example

With the default values below, Bonferroni Correction Calculator returns Bonferroni-adjusted α of 0.0050000000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Family-wise significance levelaccepts 0.01–50 %
5 %
Number of comparisonsminimum 1
10
An observed p value to testaccepts 0–1
0.008

Results

Bonferroni-adjusted α
0.0050000000
Decision for your p value
Not significant after correction
Bonferroni-adjusted p value
0.08000000
Family-wise error rate without correction
0.40126306

Step by step

  1. 1Values used
  2. 2Bonferroni correction
  3. 3Bonferroni-adjusted α= 0.0050000000
  4. 4Decision for your p value= Not significant after correction
  5. 5Bonferroni-adjusted p value= 0.08000000
  6. 6Family-wise error rate without correction= 0.40126306

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 10 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

For 10 comparisons at 5%?

The adjusted threshold is 0.005, so a p of 0.008 no longer counts as significant — and without correction the family-wise error rate would be about 40%.

Is Bonferroni too strict?

Often, yes. The Holm-Bonferroni or Benjamini-Hochberg procedures control error while retaining more power.

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