Observed arrival · 2026-11-15
CFU Calculator: microbiology calculations with the working shown
A set of free calculators for estimating CFU/mL and CFU/g, converting OD600 readings to cell-density estimates, and planning serial dilutions.
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- Microbiology students and lab workers checking calculations
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- The page warns that OD600-to-cells/mL needs calibration for the organism, medium, instrument, and measurement range.
Field notes
The methods material distinguishes viable-count estimates from optical-density estimates and cautions that a CFU result reflects colonies recovered under particular growth conditions. For OD600 conversion, the page says the calibration must match the organism, medium, instrument, and measurement range. Its dilution example also makes the cumulative-factor rule explicit: two successive 1:10 steps yield a factor of 100.
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