CFU per mL Calculator
Calculate Colony Forming Units (CFU) per mL from agar plate colony counts, volume plated, and dilution exponent.
Input Parameters
Enter details for calculation.
CFU per mL
Standard Format
Expert Tip
Agar plates with 30 to 300 colonies are considered statistically ideal. Outside of this range, counts are prone to sampling error or crowding.
Calculation Methodology & Details
Formula
For example, plating 0.1 mL of a 10⁻⁵ dilution and getting 150 colonies yields: CFU/mL = (150 × 10⁵) / 0.1 = 1.5 × 10⁷ CFU/mL.
Important Disclaimer
The calculations provided are for educational and general planning guidelines only. They do not replace professional laboratory or environmental analysis or certified scientific advice.
How to Calculate CFU/mL
Follow these steps to calculate sample concentration:
Count colonies
Perform colony count on a plate within the 30-300 countable range.
Enter Dilution & Vol
Input dilution exponent (e.g. -5) and the plated volume.
Convert units
Select whether the volume was measured in milliliters or microliters.