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Mean kinetic temperature (MKT) and excursion assessor

Paste logger readings from storage or a cargo shipment: MKT per ICH Q1A(R2), time out of range, and which figure actually governs the excursion.

Vaccines, biologics and most cold-chain pharmaceutical distribution.

Summary

Paste data or load the example to see MKT and excursion statistics.

MKT characterises the thermal exposure of a period; whether an excursion is acceptable depends on product-specific stability data, not on MKT staying below the label condition. This quick check does no data-quality gating — for a mapping study use the full workflow.

A worked example

A refrigerated consignment arrives after a 40-hour road leg. The logger shows two hours at 14 C partway through and 2-8 C the rest of the way. The receiving team wants to know what to put in the deviation record.

What you start with

Storage condition
Refrigerated, 2 to 8 C
Journey length
40 hours, readings every 15 minutes
The excursion
8 readings at 14.0 C

The arithmetic

  1. 01

    Check the sampling interval before computing anything, because MKT here is reading-weighted.

    evenly spaced at 15 min, so MKT is valid: MKT 5.77 C, mean 5.45 C

  2. 02

    Decide which figure governs from the shape of the journey.

    39.75 h of record, under the 72 h convention, so this is a short journey and the worst single run governs

  3. 03

    Characterise that run against the limit it broke.

    14.0 C is 6.00 C above the 8 C limit, for 120 minutes, which is 5.0 % of the record

Report 6.0 C above the limit for 120 minutes, and read that against the product stability data. Do not report the MKT.

The MKT is 5.77 C and the mean 5.45 C. Both sit comfortably inside 2-8 C while two hours at 14 C sit inside the record, because 38 compliant hours dilute them almost completely. Reporting either one would describe a shipment that never breached its limits, and the only reason this tool does not is that it checks the journey length before choosing a summary. Over a three-week sea crossing the same arithmetic reverses and MKT becomes the honest figure, while the single run becomes the footnote.

How the calculation works

  1. 01MKT (K) = (ΔH/R) / −ln[ Σ e^(−ΔH/(R T_i)) / n ], with T_i in kelvin and ΔH/R = 10 000 K (ΔH = 83.144 kJ/mol, R = 8.3144 J/(mol·K)).
  2. 02Excursions are consecutive readings outside the limits; duration = time from the first to the last reading in the run plus one sampling interval (median spacing).

Limitations

  • MKT summarises thermal exposure for storage assessment. It does not justify an excursion above a product's limit — product-specific stability data do that.
  • This is a quick check, not a mapping analysis: no data-quality gating for gaps, flatlines or unit ambiguity.
  • Readings are assumed to be in °C.

Frequently asked questions

Why is MKT higher than the average temperature?
Because degradation rates rise exponentially with temperature (Arrhenius), warmer periods are weighted more heavily. MKT equals the mean only for a constant temperature. Twenty-seven days at 22 °C with three days at 35 °C gives a mean of 23.30 °C and an MKT of 24.42 °C: against a 25 °C limit the mean passes with 1.70 °C of margin and the MKT with 0.58 °C, so three days in thirty took two thirds of the headroom.
Can MKT be used to release a product after an excursion?
Only if the product's stability documentation explicitly allows it. Regulators expect excursion assessments to rest on product-specific data; MKT is for characterising storage conditions over a period.
What format does the paste box accept?
One reading per line; commas, semicolons, tabs or spaces as separators; the last number on each line is the temperature and anything before it is read as a timestamp if it parses (ISO 8601 works best). Header lines are skipped.

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Read the theory

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