What are the four device classes under the EU MDR?

The MDR defines four risk classes in ascending order of risk: Class I (low risk), Class IIa (medium-low), Class IIb (medium-high) and Class III (high risk). The class sets your conformity assessment route and decides whether a Notified Body has to be involved.

Does a Class I device need a Notified Body?

Most Class I devices can self-declare conformity without a Notified Body. The exceptions are sterile devices, devices with a measuring function and reusable surgical instruments, which do need Notified Body involvement, but only for those specific aspects.

Who confirms my device classification?

You work out the class yourself using Annex VIII, but for every class above Class I your Notified Body reviews and confirms it during conformity assessment. Competent authorities can rule on disputes. Treat any tool-based result as a preparatory assessment rather than a final decision. We always recommend that you discuss your regulatory classification with an expert.

MDR Device Classification

Under the EU Medical Device Regulation (MDR 2017/745), every medical device is assigned to one of four risk classes (Class I, IIa, IIb or III) using the 22 classification rules in Annex VIII. Your class sets the conformity assessment route, decides whether a Notified Body has to be involved, and drives how much technical documentation you need.

What are the device classes under the EU MDR?

Devices sit in one of four classes, in ascending order of risk. The higher the class, the greater the regulatory scrutiny.

Class I is low risk. Most Class I devices can self-declare conformity. Sterile devices, devices with a measuring function and reusable surgical instruments still need a Notified Body, but only for those aspects.
Class IIa is medium-low risk, and a Notified Body carries out the conformity assessment.
Class IIb is medium-high risk, assessed by a Notified Body with closer scrutiny of the technical documentation.
Class III is high risk. As a rule of thumb, a device is Class III if it contacts the heart, the central circulatory system or the central nervous system, is absorbed by the body, or is an active implant. It gets the most scrutiny of all.

How is a medical device classified under the MDR?

Classification follows the 22 rules in Annex VIII, grouped as non-invasive (Rules 1–4), invasive (Rules 5–8), active (Rules 9–13) and special rules (Rules 14–22). Which rule applies comes down to a few things:

Duration of use: transient (under 60 minutes), short-term (up to 30 days) or long-term (over 30 days).
Invasiveness: whether the device enters the body, and if so through a body orifice or surgically.
Whether it is active: whether it relies on a source of energy other than the body or gravity.
Part of the body affected: contact with the central circulatory or central nervous system pushes a device into the highest classes.

Where several rules apply, the one that gives the higher class wins. The MDR also up-classified many devices compared with the old MDD, so a device that used to be Class I may now sit in Class IIa or above.

How is software classified? (Rule 11)

Software as a Medical Device (SaMD) has its own rule. Rule 11 places software anywhere from Class I to Class III, based on the clinical decision it informs and how much harm a wrong one could do.

Our SaMD classification guide is the full walkthrough: the qualification test (is your software even a medical device?) and each Rule 11 tier in turn.

What does your classification determine?

The conformity assessment route and whether a Notified Body is required.
The scope of your technical documentation (MDR Annexes II and III).
The depth of clinical evaluation and post-market surveillance you must maintain.

Frequently asked questions

What are the four device classes under the EU MDR?: The MDR defines four risk classes in ascending order of risk: Class I (low risk), Class IIa (medium-low), Class IIb (medium-high) and Class III (high risk). The class sets your conformity assessment route and decides whether a Notified Body has to be involved.
How is a medical device classified under the MDR?: Classification follows the 22 rules in Annex VIII of MDR 2017/745. The rule that applies depends on the duration of use (transient, short-term or long-term), how invasive the device is, whether it is active, and which part of the body it touches. Where several rules apply, the one that gives the higher class wins.
Does a Class I device need a Notified Body?: Most Class I devices can self-declare conformity without a Notified Body. The exceptions are sterile devices, devices with a measuring function and reusable surgical instruments, which do need Notified Body involvement, but only for those specific aspects.
Who confirms my device classification?: You work out the class yourself using Annex VIII, but for every class above Class I your Notified Body reviews and confirms it during conformity assessment. Competent authorities can rule on disputes. Treat any tool-based result as a preparatory assessment rather than a final decision. We always recommend that you discuss your regulatory classification with an expert.

Working out your class is only the first step. You can also compare the available MDR classification tools to see which kind of support fits where you are.

This page is preparatory guidance based on MDR 2017/745, not legal advice. Your final classification is confirmed by your Notified Body during conformity assessment.

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