F 0 value for autoclave

How to do calculation of F 0 value

Hello, Atmaram, and welcome.

The physical calculation of F0 is a function of time and temperature. The direct formula is this one:



  • F0 is the process lethality [[email protected]°C]
  • D121 is the time needed at 121.1°C to reduce 90% of the population (1 log reduction) units: [[email protected]°C]
  • T is the actual product temperature (or the mean temperature during the time interval: ∆t units: [°C]
  • Z is the temperature coefficient, which is the difference in temperature needed to change resistance “D” by a factor of ten. For moist heat processes, it can be considered constant at 10°C. units: [°C]
  • ∆t is the time interval for accumulation of process lethality F0. units: [min]

This formula calculates the F0 accumulated in a time interval, and you must sum all F0 of each minute to calculate the F0 accumulated during the whole process.

If you want to calculate the process lethality by biological approach (FBio) the formula is this one:

FBio = D121 * (log N0 - log Nf)

*N0 is the initial population of microorganism

  • NF is the final population: which to comply with USP requirements for moist heat sterilization of compendial article, it can be replaced with the SAL (Sterility Assurance Level) of 10^-6, wich is a probability of 1 un 1,000,000.

I hope this is helpful. Let me know if you need me to elaborate further, or if you have a more specific questeion.

This topic was automatically closed 10 days after the last reply. New replies are no longer allowed.