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🔬 Mutation Frequency Calculator

Calculate mutation frequency from the number of mutants observed out of a total population screened.

1
colonies/cells
2
cells

What This Calculator Does

Mutation frequency describes what fraction of cells (or colonies) in a population carry a particular mutation, and is a common readout in mutagenesis and genotoxicity screening assays.

The Formula

Mutation frequency is simply Mutant count / Total population screened. Because this raw fraction is usually a very small number, it is conventionally also expressed as mutants per million (106) cells, which this calculator provides alongside the raw value.

  • Mutant count is the number of mutant colonies or cells observed.
  • Total population screened is the total number of cells or colonies plated/tested.

This is a general educational and lab-reference calculation. It reports observed mutation frequency only; it does not correct for factors like plating efficiency, selection stringency, or spontaneous background mutation rate, which should be accounted for separately in a full analysis.

Last reviewed August 2026