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F₀ Sterilization Lethality Calculator

Estimate cumulative F₀ lethality from time and temperature intervals using a 121.1 °C reference temperature and z = 10 °C.

Calculate F₀ lethality

Enter one interval per line as minutes, temperature in °C. Each temperature is treated as constant for that interval.

Reference: Tref = 121.1 °C; z = 10 °C

In short: Enter the duration and temperature for each exposure interval to estimate cumulative F₀ in equivalent minutes at the reference temperature.

Formula

F₀ = Σ [Δtᵢ × 10^((Tᵢ − Tref) / z)]
Tref = 121.1 °C; z = 10 °C

For each row, the calculator multiplies the interval duration (minutes) by its temperature lethality factor, then sums the interval contributions. This is an interval-sum calculation: it treats each entered temperature as constant for the duration in that row. It does not interpolate between values.

EMA/CHMP/CVMP/QWP/850374/2015 (2019), section 6, defines F₀ for saturated-steam sterilisation as equivalent minutes at 121 °C using a theoretical z-value of 10. This tool follows the 121.1 °C reference used in the tool specification; the difference needs confirmation against the controlled pharmacopoeial text before release.

Assumptions and defaults

  • Enter one interval per line as minutes, temperature °C.
  • Each interval has a positive duration. Temperature is treated as constant within that interval.
  • Tref is fixed at 121.1 °C and z is fixed at 10 °C for this calculator. EMA/CHMP/CVMP/QWP/850374/2015 (2019), section 6, defines F₀ using a 121 °C reference and theoretical z = 10; the precise reference-temperature convention remains flagged for Admin verification above.
  • The result is an arithmetic sum of interval lethality contributions. Data sampling, sensor placement, heat distribution, heat penetration, product resistance, and process validation are outside this calculation.

Worked examples

  • 15 minutes at 121.1 °C gives F₀ = 15.00 minutes using the calculator’s reference temperature.
  • 1 minute at 131.1 °C gives F₀ = 10.00 minutes because the temperature is one z-value above the reference.

Limitations

This calculator reports an estimated lethality total from the entered intervals. It does not establish a sterilisation cycle, sterility assurance level, product suitability, or a release criterion. Use the validated process, product-specific data, current controlled standards, and approved site procedures to assess sterilisation performance.

References

  • European Medicines Agency, Guideline on the sterilisation of the medicinal product, active substance, excipient and primary container, EMA/CHMP/CVMP/QWP/850374/2015 (2019), effective 1 October 2019, section 6 “Definitions.” Current guideline page and official PDF.
  • European Medicines Agency, Overview of comments received on the draft guideline on sterilisation, EMA/CHMP/CVMP/QWP/366428/2018 (2019), public comments discussing 121.1 °C and Ph. Eur. 5.1.1. Official comments document. Comments are not the adopted guideline text.