How this calculator works
For directly observed independent events, rate is events divided by scored opportunities. The per-site mode treats bases times generations as the total callable exposure; account explicitly for ploidy and independent transmissions when preparing those inputs. The fluctuation zero-class method estimates mean mutation events as -ln(p0), then divides by final cells as an approximation to divisions when the inoculum is negligible. It assumes independent comparable cultures, reliable mutant detection and no selection before assay. Mutant colony counts alone are not independent event counts.
Formula
Direct rate = events/opportunities. Per-site rate = events/(callable bases × generations). Zero-class: m = -ln(p0); rate ≈ m/Nfinal. Inverse zero fraction = exp(-rate × Nfinal).
Worked example
Ten independent events over 100 generations and 1000 callable bases give 0.0001 per base-generation. A zero-culture fraction of exp(-1) with 1000000 final cells gives an estimated rate of 0.000001 per division.
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Frequently asked questions
Can I use the number of mutant colonies as events?
Not generally. Descendants of one early mutation can form many colonies. A suitable fluctuation analysis is needed.
What if every culture has mutants?
p0 is zero and the zero-class estimator is undefined. Use a method suited to the full mutant-count distribution.
Does offspring count include both parental copies?
Enter the actual scored opportunities. If your assay scores two independent alleles per offspring, incorporate that exposure in the denominator.