CFU Colony Counting Calculator

Calculate colony forming units per milliliter (CFU/mL) from plate counts with dilution factors for accurate microbial enumeration in lab samples.

Colonies Counted

Dilution Factor (e.g. 1e-6 enter 6)

Volume Plated (mL)

Number of Replicate Plates

Formula

CFU/mL = (Average Colonies) / (Dilution Factor x Volume Plated); Dilution Factor = 10^(-n); where n = number of serial dilution steps

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Free serial dilution calculator. Calculate the final concentration after multiple sequential dilution steps.