What does Class III certification mean?

Precision weight scale calibration

You can buy a bathroom scale at a cheap price. Why are some medical weighing scales so much more expensive? They look pretty much the same, and sometimes even have similar maximum weight capacity.

There are a lot of different certifications and markings out there - in this blog post, we'll be explaining some of the most important and common ones found on Charder scales.

 Why is accuracy so important?

In medical settings, patient weight is oftentimes used for diagnosis, monitoring, and medication. For example, the amount of anesthesia used for surgery is determined based on the weight of the patient, so an inaccurate weight measurement (or estimation, which is even worse!) may lead to an incorrect dosage, which could have very bad results!

In many countries, weight measurement scales are considered medical equipment if intended to be used in hospital settings, because reliability, accuracy, and safety are prioritized. In contrast, the bathroom scale you use at home is not required by law to be accurate, which is why they can be produced at very low cost.


Under the Non Automatic Weighing Instrument (NAWI) Directive used in the European Union (and accepted in many other countries/regions as an indicator of accuracy), scales are categorized into class. Different applications will require different classes - Class I is the most accurate and used for very specialized purposes, but for most medical applications, Class III is the standard.


To receive approval, medical scales must undergo a verification test, which ensure that the scale's performance, reliability, and repeatability are consistent, providing accurate results every time. These tests can only be conducted by a certified authority. If you're purchasing a medical scale for use in the European Union, then you're generally looking for one with Class III certification.

If you're outside this region, then this certification may not be legally necessary - but it is still an option that helps to ensure that you receive accurate results.

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