Original instructional diagram for A Non-Detect Is Not Zero: Report Log-Reduction Limits Correctly. Values, when shown, are illustrative; clinical images do not recommend a dose.
Record the detection statement literally
A reported non-detect means the method did not detect a quantity under its stated conditions. It does not establish an actual count of zero. Keep the detection limit and the sampling basis available when reporting a lower-bound reduction.
Use Log Reduction Calculator to work through these inputs while keeping the displayed assumptions in view.
Do not confuse reduction with validation
A reduction calculated from two counts does not prove a process meets a regulatory or laboratory validation criterion. Comparable sampling, appropriate controls and a justified detection method remain necessary. The calculator does not convert an uncertain count into evidence of sterilization.
This question belongs to the Bio laboratory calculators group within Biology calculators.
Read the calculation on its stated basis
Log10 reduction = log10(initial count ÷ remaining count); percent reduction = 100 × (1 − remaining/initial).
Retain the input definitions and units with the result. A later comparison should use the same basis; a change in method is a new scenario, not simply a more precise version of the old number.
Keep related questions separate
Mutation Frequency Calculator addresses a related part of the measurement or interpretation task. Check its own method before carrying a value from one tool to the other.
For a related perspective, read Mutant Frequency Is an Endpoint Observation, Not a Mutation Rate.
For tools in other subjects, return to GreenCalc. Keep the calculator result with its assumptions rather than using a link or a matching unit as evidence that two models are interchangeable.
By GreenCalc · Updated 2026-11-05