CFU/mL Viable Plate Count

Colony-forming units per mL of the original sample from colonies counted, dilution factor, and volume plated.

Run the calculator

Example

You enter

Colonies counted 150
Dilution factor (e.g. 1e-5 or 100000) 0.00001
Volume plated (mL) 0.1

You get

CFU/mL 150000000

Details, formula, and sources

With a countable-range validity flag.

CFU/mL = colonies / (dilution_factor * volume_plated). The dilution factor is accepted as a fraction (1e-5) or a times value (100,000) and normalized to the same result.

Per the FDA Bacteriological Analytical Manual (BAM) Chapter 3 (Aerobic Plate Count) and APHA Standard Methods, by name; both public/free.

Free at fda.gov/food/science-research-food/laboratory-methods-food.

Estimate. AHJ and licensed professional govern.

Field names used by the API: colonies, dilution_factor, volume_ml, cfu_per_ml

Plated volume spread/pour/spiral methods change the effective plated volumeFDA BAM Ch. 3