Serial Dilution Plate Count Calculator
Calculate cell density (CFU/mL) by averaging colony counts from a serial dilution series, automatically filtering for statistically valid plates.
Input Parameters
Enter details for calculation.
Average Cell Concentration
Expert Tip
Only plates with colony counts between 30 and 300 should be used in calculations. Below 30 is too variable (TFTC), and above 300 has too much overlap (TNTC).
Calculation Methodology & Details
Formula
Plates with counts outside 30-300 are statistically prone to sampling error and are flagged as TNTC (Too Numerous to Count) or TFTC (Too Few to Count).
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 Process Dilution Series
Steps to evaluate cell counts across dilutions:
Input Plate Data
Enter dilution exponents and counts for each agar plate.
Filter Countable Plates
Check which plates fall into the statistically valid range (30-300).
Calculate Average
The calculator ignores invalid plates and averages the CFU/mL of the rest.