MKT · USP <1079> · °C or °F

Mean kinetic temperature calculator (MKT)

Know whether the hot port days broke the storage limit before release.

Last updated 2026-09-28. Math runs in your browser, no data leaves your computer.

Paste the readings straight from the data logger, one per line. The plain average hides short hot spells, which is why USP writes its controlled room temperature rule against mean kinetic temperature and not the average.

One reading per line at a fixed interval; if a line carries a date or time, keep the temperature as the last number on the line.

Match the logger setting, because a °F file read as °C gives a result that is nonsense.

The default is 83.144 kJ/mol ÷ 0.0083144 kJ/(mol·K), exactly 10,000 K, used when the product has no measured value.

Type the MKT ceiling from the label, the spec or the supply agreement, in the same unit as the readings.

Before the booking, screen the name on the invoice. Shipment pre-check is on the paid plans, from USD 59 a month.

General guidance only. Verify against the cited primary sources before you commit to a shipment, declaration, or contract.

How the MKT formula works

The tool converts every reading to kelvin (°C + 273.15, and °F first to °C by (°F − 32) × 5/9), raises e to the power −ΔH/(R × T) for each one, averages those terms, and takes the natural log. Mean kinetic temperature is then TK = (ΔH/R) ÷ −ln(mean of e−ΔH/(RT)), converted back to your unit.

This is the equal interval form of the formula given in USP General Chapter <1079>, Good Storage and Distribution Practices, as reproduced in Jenkins, Cancel and Layloff, BMC Public Health 22:300 (2022), which also gives the default activation energy of 83.144 kJ/mol and R of 0.0083144 kJ/(mol·K). The USP text itself sits behind a subscription, so check your edition before quoting it in a deviation report.

The exponential weighting is the whole point. A reading 10 degrees above the rest pulls MKT up far more than a reading 10 degrees below pulls it down, which matches how degradation actually speeds up in heat. It is also why USP General Chapter <659>, as summarised in the same paper, lets controlled room temperature product see excursions between 15 °C and 30 °C only while the MKT stays at or below 25 °C.

Worked example: a hot week on the quay

The booking. A heat sensitive intermediate ships under a supply agreement that caps MKT at 25 °C (77 °F) for the voyage. The logger shows 25 daily readings at 22 °C and 5 at 38 °C while the box waited at the transshipment port, and the plain average is (25 × 22 + 5 × 38) ÷ 30 = 24.7 °C, which looks fine on paper.

The failure. Run the same 30 readings through the formula with ΔH/R of 10,000 K and the MKT comes out at 27.1 °C (80.8 °F), over the cap. The buyer's quality team can reject the lot on that number alone, whatever the average says. Either the routing changes, or the product does.

The fix. Rebook on a direct service where the dwell at 38 °C falls to 2 days. The log becomes 28 readings at 22 °C and 2 at 38 °C, the MKT drops to 24.4 °C (75.9 °F), and the lot clears the 25 °C cap with the certificate intact.

Shipping a liquid through the same heat? The liquid expansion and ullage calculator shows how much room the drum or tank needs at the top temperature at /tools/chemicals/liquid-expansion-ullage-calculator.

Need the density at the logged temperature for a weight check? The density at temperature calculator corrects an SDS value for heat at /tools/chemicals/density-at-temperature-calculator.

Frequently asked

What is mean kinetic temperature?

It is the single steady temperature that would cause the same total degradation as the swinging temperatures a product actually saw. Because reaction rates climb exponentially with temperature, a few hot days count for more than the same number of cool ones, so MKT always sits at or above the plain average. The definition and formula are set out in USP General Chapter <1079>.

Why is ΔH/R set to 10,000 K?

The default activation energy used for MKT is 83.144 kJ/mol, and dividing by the gas constant of 0.0083144 kJ/(mol·K) gives exactly 10,000 K. Jenkins, Cancel and Layloff (BMC Public Health, 2022) use that default where no product stability data exists, citing USP. If your supplier has measured an activation energy for the product, divide it by R and type the result into the box.

Do the readings have to be at equal intervals?

Yes, this form of the formula weights every reading the same, so the logger has to record at a fixed interval such as every 15 minutes or once a day. If the log mixes intervals, resample it to one interval first, otherwise a burst of readings during a hot spell will be over counted.

Can I paste a logger export with dates and times?

Yes, as long as the temperature is the last number on each line. The tool reads one reading per line and takes the last number it finds, so a CSV row like 2026-09-01 08:00, 22.4 counts as 22.4. Use a full stop for decimals, since a decimal comma is read as a separator.

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Sourzi shows what official files say. It is not customs or legal advice. For a binding answer, ask a licensed customs broker, a CBP ruling or an Australian Border Force Tariff Advice.

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