Multiplicity of Infection (MOI) Calculator
Compute total plaque-forming units added and the multiplicity of infection (MOI) from viral stock titer, volume applied and number of cells.
How to Use the Multiplicity of Infection (MOI) Calculator
- Enter the number of target cells.
- Enter viral stock titer in PFU/mL.
- Enter volume of inoculum in mL.
- Click Calculate to see total PFU and MOI.
Use Cases
- •Virus infection protocols.
- •Plaque reduction assays.
- •Teaching virology lab technique.
Formula
Total PFU = titer (PFU/mL) × volume (mL). MOI = total PFU / cells. Required PFU for target MOI = MOI × cells.
Frequently Asked Questions
What MOI should I use?
Depends on the virus and assay: low MOI (0.01–0.1) for multi-cycle propagation, high MOI (3–10) for synchronous single-cycle experiments.
How accurate is PFU titer?
Plaque assays have roughly ±30% variability between replicates. For precision, titer the same stock in parallel with your experiment.
Medical disclaimer
Educational only. Handling live virus requires appropriate biosafety-level authorization and training.