Enter the number of mutants observed (or other counted mutation outcomes) and the total number of cells per culture into the calculator. The calculator evaluates the mutation frequency (mutant fraction), which is often reported as “mutants per cell.” Note: this simple ratio is not the same as the true mutation rate per cell division / per generation, which typically requires additional modeling (e.g., fluctuation analysis) and growth information.

Mutation Frequency (Mutant Fraction) Calculator

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Enter any 2 values to calculate the missing variable

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Mutation Frequency (Mutant Fraction) Formula

The following two example problems outline the steps and information needed to calculate the mutation frequency (mutant fraction) from a simple count ratio.

MF = m/N
  • Where MF is the mutation frequency (mutants per cell; a dimensionless fraction)
  • m is the number of mutants observed (e.g., mutant colonies/cells counted)
  • N is the number of cells per culture

To calculate the mutation frequency, divide the number of mutants observed by the number of cells per culture.

How to Calculate Mutation Frequency?

The following example problems outline how to calculate mutation frequency.

Example Problem #1:

  1. First, determine the number of mutants observed.
    • The number of mutants observed is given as: 100.
  2. Next, determine the number of cells per culture.
    • The number of cells per culture is provided as: 6,000.
  3. Finally, calculate the mutation frequency using the equation above: 

MF = m/N

The values provided above are inserted into the equation below and computed.

MF = 100/6,000 = 0.0167 (mutants per cell)

Example Problem #2: 

For this problem, the variables required are provided below:

number of mutants observed = 500

number of cells per culture = 1,500

Test your knowledge using the equation and check your answer with the calculator.

MF = m/N = ?