TCID50 Guide
How to Calculate TCID50 from Endpoint Dilution Data
A practical guide to calculating TCID50/mL from endpoint dilution assay data using positive and total well counts.
What TCID50 Measures
TCID50 is the dilution or dose that infects 50 percent of test units, commonly wells or cultures. In endpoint dilution assays, the input data are the dilution series, inoculation volume, and the number of positive wells out of the total wells at each dilution.
Basic Calculation Workflow
Arrange the dilutions from strongest to weakest, record positive and total wells, check that positive counts generally decrease as dilution increases, then calculate the 50 percent endpoint. BioCalculator reports TCID50/mL so the result can be compared across inoculation volumes.
When to Use a Calculator
A spreadsheet can work, but TCID50 calculations are easy to mis-copy when several dilution rows are involved. A dedicated calculator is useful as a quick independent check before the result is used for virus stock planning.