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Temperature measurements

Clinical thermometer systems


Clinical thermometer systems ISO80601-2-56

Body temperature measurement is an important tool that can assist in the early diagnosis of infectious or other disease. Just like any other thermometry method, ensuring on-going, reliable clinical temperature measurement requires the periodic calibration of the clinical thermometer (and its calibrator) by an accredited laboratory to ensure measurement traceability.

NPL has significant leading expertise in temperature measurement and is able to offer clinical thermometer calibration and related services. 

The ISO standard relating to medical electrical equipment (ISO 80601-2-56:2017) specifies temperature and humidity environments in which portable thermometers must be proven to operate. NPL can perform calibrations of clinical thermometers to meet this standard, using the combination of a calibration system traceable to national temperature standards placed inside an environmental chamber. A series of temperatures over a range of ambient temperatures (from 15 °C to 45 °C) and relative humidities (from 20 %rh to 80 %rh) can be accommodated. The time response of the device to applied heating and cooling can also be measured, in accordance with the standard.

Some examples of the services we provide are listed below. Our diverse skill set enables us to provide bespoke solutions. If you don’t see what you are looking for please contact us to discuss your specific requirements.

Contact us

Clinical thermometer calibration
Thermal imaging system assessment services
Consultancy services/ bespoke advice

Why regular calibration matters

Whether contact or non-contact measurement of temperature is performed, all thermometers have an uncertainty associated with the measurements they perform.

The relevant ISO standard for clinical thermometry stipulates that a clinical temperature measurement device must have a measurement uncertainty associated with the device of not greater than to ± 0.3 °C (k = 2) when manufactured.

There are however, a number of other factors which over time can impact this measurement uncertainty, for example:

  • Drifts in the electronics of the thermometer over time
  • A shock to the device, such as dropping or extended exposure to a strong heat source
  • Prolonged use without performance confirmation


In addition there are other factors which contribute further to the measurement uncertainty of the clinical thermometer, some of which can be very significant:

  • Incorrect use of the device
  • The body site chosen for the temperature measurement
  • The resolution of the thermometer device (generally 0.1 °C)

Regular, traceable calibration of the clinical thermometer by an accredited provider combined with training programmes which ensure consistent use of the device enables users to have confidence in the temperature data required to undertake reliable triage and diagnosis decisions. Traceable accredited calibration will reliably identify any changes in the thermometer performance. We have the expertise to provide both accurate and authoritative calibration services for both contact and non-contact thermometers used for clinical temperature measurement. More details are given below.


View Dr Graham Machin’s presentation on the challenges of non-contact body temperature measurement.

Clinical Temperature Measurement Presentation

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