Calculator
Colony Count Calculator
Predict the expected number of colonies for a given bacterial concentration.
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All fields required unless notedEnter your values and press Calculate to see the result.
Formula & Clinical Notes
Formula
Colonies = CFU/mL × Volume plated (mL) / Dilution factor
Clinical Notes
Colonies = CFU/mL × volume plated / dilution factor. This helps plan the dilution needed to obtain a countable plate (25–250 colonies). For example, a 10⁻⁴ dilution of a 10⁶ CFU/mL suspension plated at 0.1 mL yields about 10 colonies.
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