Mean Kinetic Temperature (MKT) Calculator
Calculate mean kinetic temperature (MKT) from equally spaced temperature readings and compare it with a chosen numerical threshold.
Mean kinetic temperature (MKT) is a single temperature that would cause the same total chemical degradation as the varying temperatures a product actually went through. Under customary activation-energy assumptions, warmer periods usually raise MKT above the arithmetic mean; this is not a universal inequality for every custom activation energy. Pharmaceutical warehouses, distributors and cold-chain teams use it to assess storage and shipping temperature records.
How to use this tool
- Paste temperature readings taken at equal intervals, separated by commas, spaces or new lines.
- Choose °C or °F.
- Keep the default activation energy of 83.144 kJ/mol unless you have a product-specific value.
- Optionally enter the storage limit to compare against.
Formula
MKT = (ΔH ÷ R) ÷ −ln[(e^(−ΔH/RT₁) + e^(−ΔH/RT₂) + … + e^(−ΔH/RTₙ)) ÷ n]
ΔH is the activation energy (default 83.144 kJ/mol), R is the gas constant (8.3144 J/mol·K), and T₁ to Tₙ are the readings in kelvin. With the default values ΔH ÷ R is exactly 10,000 K. The result is converted back to your unit.
Example
Two equal periods at 20 °C and 30 °C average 25 °C. In kelvin they are 293.15 K and 303.15 K. The average of e^(−10000/293.15) and e^(−10000/303.15) equals e^(−33.399), so MKT = 10,000 ÷ 33.399 = 299.41 K = 26.26 °C. That is 1.26 °C above the arithmetic mean, because the warm period does more damage, and it breaches a 25 °C limit even though the average does not.
Frequently asked questions
Why is MKT higher than the average temperature?
Reaction rates rise exponentially with temperature (the Arrhenius relationship), so an hour at 30 °C does more harm than an hour at 20 °C saves. MKT weights each reading by its effect, which pulls it toward the warmer readings.
What MKT applies to controlled room temperature?
Under the USP definition of controlled room temperature (20–25 °C, with excursions allowed between 15 and 30 °C), 25 °C is one MKT criterion, not a complete acceptability test. Peak temperature, duration, observation window, label and product stability also matter.
Do the readings have to be evenly spaced?
Yes. The formula gives every reading equal weight, so use readings logged at a fixed interval, such as raw hourly values. Averaging temperatures before the exponential step hides excursions. Unequal intervals require time weighting, which this tool does not implement.
Can MKT justify a short heat excursion?
It provides a numerical thermal summary, not an acceptance decision or replacement for stability data. Some damage, such as melting, freezing or phase separation, is not captured by MKT at all.
Sources
Last updated: 2026-10-30