Cold Chain Temperature Excursion Calculator
Paste data logger readings to get time above and below range, excursion events, longest excursion, time in range and mean kinetic temperature (MKT).
Summarize uniformly spaced temperature readings as estimated time outside chosen limits, separate high/low events and mean kinetic temperature. Use the product’s specified temperature range; the 2–8 °C defaults are an example, not a universal food or medicine rule. This tool summarizes a record and cannot authorize product release.
How to use this tool
- Paste the logger readings in time order, separated by commas, spaces or new lines.
- Enter the logging interval and choose °C or °F.
- Set the lower and upper limits of the allowed range.
- Optionally enter the stability budget from the manufacturer to see how much excursion time is left.
Formula
Time out of range = number of out-of-range readings × logging interval
MKT = (ΔH/R) ÷ (−ln( (e^(−ΔH/RT₁) + … + e^(−ΔH/RTₙ)) ÷ n )) − 273.15
Each sample represents one whole logging interval, so n samples represent n intervals; a record containing only start/end timestamps spans n − 1 intervals instead. No interpolation is performed. Adjacent out-of-range readings on the same side form one event. MKT uses absolute kelvin, R = 0.008314462618 kJ/mol·K and a chosen activation energy; 83.144 kJ/mol is a conventional example. Calculations include up to 20,000 readings; event tables show 400 rows.
Example
A logger set to 15 minutes records 5, 6, 9, 10, 7, 5, 1 and 4 °C against a 2–8 °C range. The readings 9 and 10 form one high excursion of 30 minutes, and the single reading of 1 °C is a low excursion of 15 minutes. That makes 2 events and 45 minutes out of range, so 62.5% of the two-hour record was within limits.
Frequently asked questions
Why is MKT higher than the average temperature?
MKT weights warm readings more heavily because degradation speeds up exponentially with temperature (the Arrhenius relationship). A record that averages 5 °C but includes an hour at 15 °C shows an MKT above 5 °C.
Does an excursion mean the product must be destroyed?
Follow manufacturer stability data and quality procedures. For vaccine excursions, CDC directs staff to isolate and label affected stock DO NOT USE while seeking a viability determination; do not automatically discard it.
Should I rely on MKT for 2–8 °C products?
MKT alone cannot establish product suitability or account for freezing damage and phase changes. Its kinetic assumptions must be justified for the product. The optional cumulative time budget is only arithmetic and does not replace temperature-specific stability evidence.
How are readings exactly on the limit treated?
A reading equal to a limit counts as in range. Values are compared exactly as entered, so keep the same decimal places your logger reports.
Sources
Last updated: 2026-10-30