FDA device classification assigns every medical device to one of three risk-based classes under Section 513 of the FD&C Act. The class determines which controls apply and which submission the FDA requires, such as a 510(k) or Premarket Approval.
Definition and legal basis
FDA device classification assigns every medical device to one of three classes: Class I, II, or III. The deciding factor is the risk of the device. According to the FDA, Class I covers the devices with the lowest risk and Class III those with the highest. Among other things, the class determines which regulatory controls apply and what type of premarket submission the FDA requires.
The statutory basis is Section 513 of the Federal Food, Drug, and Cosmetic Act (FD&C Act), codified in the US Code as 21 U.S.C. 360c. The procedure for classification and reclassification is governed, among other provisions, by 21 CFR Part 860 (“Medical Device Classification Procedures”). It defines the class as one of three categories of regulatory control.
According to the FDA, the class depends on the intended use and the Indications for Use. Under 21 CFR 860.7, the assessment of safety and effectiveness also takes into account the persons for whose use the device is represented and the conditions under which it is used. The same hardware can therefore be classified differently depending on the claimed use.
The three classes and their controls
Assignment follows the question of whether general controls are sufficient or whether more is needed. The following table summarizes the definitions in 21 CFR 860.3 and Section 513(a)(1).
| Class | Controls | Criterion |
|---|---|---|
| Class I | General Controls | General Controls are sufficient to provide reasonable assurance of safety and effectiveness. Even where information is insufficient, a device belongs here if it is not life-sustaining or life-supporting and does not present an unreasonable risk. |
| Class II | General Controls and Special Controls | General Controls alone are not sufficient. Special Controls can be established for the device. |
| Class III | Premarket Approval | Approval before the device is placed on the market is required, for example because the device is life-sustaining or life-supporting or presents a potentially unreasonable risk. |
General Controls are the controls under Sections 501, 502, 510, 516, 518, 519, and 520 of the FD&C Act. According to the FDA, they apply to all medical devices unless a regulation exempts a device. The FDA lists, among others, registration and listing, premarket notification, reporting of adverse events, unique device identification (UDI), and good manufacturing practice.
Special Controls are added for Class II. 21 CFR 860.3 names as possible examples performance standards, performance testing, postmarket surveillance, patient registries, and guidelines. Which Special Controls apply to a device type is stated in its classification regulation or classification order.
How a device is classified
The FDA states that it has defined about 1,700 generic device types and grouped them into 16 medical specialty panels. Each classified type has a classification regulation in one of Parts 862 to 892 of Title 21 of the Code of Federal Regulations, with a seven-digit number, a description (identification), and the class. Examples are Part 870 for cardiovascular devices and Part 880 for general hospital and personal use devices.
The FDA also assigns a three-letter product code. In the Product Classification Database, a record shows, among other things, the regulation number, class, submission type, and medical specialty. For the record FLK (Clinical Mercury Thermometer), it lists (as of October 5, 2026) regulation 880.2920, Class 2, and the entry “510(K) Exempt.”
If it is unclear how the FDA classifies a device, it recommends a request under Section 513(g) (Request for Information, subject to a fee). An early discussion of classification and pathway is possible in a Pre-Submission. The FDA can also change the class of an existing type under Section 513(e), on its own initiative or on request, by administrative order (reclassification).
Exemptions from 510(k)
The class alone does not decide the submission. Under Section 510(l), Class I devices do not need a 510(k) by law, except where the device is of substantial importance in preventing impairment of human health or presents a potentially unreasonable risk. For Class II, the FDA publishes lists of device types that no longer need a 510(k) (Section 510(m)). Under 21 CFR 860.15, the classification regulation states which requirements are exempted, and an exemption is granted only if those requirements are not necessary to assure safety and effectiveness.
The limits of an exemption are set out in the respective “xxx.9” provision of the medical specialty. 21 CFR 880.9, for example, states that a 510(k) is still required despite an exemption if a device is intended for lay use although it was previously intended only for health care professionals. A different fundamental scientific technology also triggers a 510(k). The clinical thermometer under 21 CFR 880.2910 is an example: Class II, exempt subject to the conditions and limitations of 880.9.
From class to approval pathway
The FDA describes the connection as follows: if a device is Class I or II and not exempt, a 510(k) Premarket Notification is needed. In it, the manufacturer shows that its device is substantially equivalent to a legally marketed predicate device (see Substantial Equivalence and Predicate Device). For Class III, the FDA requires a PMA (Premarket Approval). The exception is devices that were marketed before May 28, 1976 (preamendments devices) and for which the FDA has not yet required a PMA. For them, a 510(k) is sufficient.
A new device that was not marketed before that date is automatically Class III under Section 513(f)(1), unless it is substantially equivalent to a classified device or is classified through a request. For this request there is the De Novo classification request under Section 513(f)(2): it leads to classification into Class I or II and, under 21 CFR 860.200, is available after a “not substantially equivalent” decision on a 510(k) or without a predicate device. The FDA can decline the request if the device is not of low to moderate risk. If granted, it publishes the classification order, including the Special Controls, in the Federal Register.
Comparison: classification under the MDR
In the EU, the MDR (Medical Device Regulation) applies. Under Article 51(1), devices are classified into Classes I, IIa, IIb, and III, taking into account their intended purpose and the associated risks. Annex VIII with 22 classification rules is decisive. The rules are applied according to the intended purpose, and if several rules apply, the strictest one prevails (Annex VIII, Sections 3.1 and 3.5). For software that provides information used to take decisions with diagnosis or therapeutic purposes, Rule 11 generally provides for at least Class IIa.
Unlike with the FDA, there is no classification regulation per device type, but rules that must be applied to every device. For Class I, the manufacturer declares conformity itself under Article 52(7). For sterile devices, devices with a measuring function, and reusable surgical instruments, a notified body (a conformity assessment body designated under the MDR) is involved for these aspects. In the event of a dispute between the manufacturer and the notified body, the competent authority decides (Article 51(2)).
The FDA Classes I, II, and III cannot simply be mapped to the MDR Classes I, IIa, IIb, and III. We have no documented conversion, so this text gives none. Both systems do require, however, that the device meets the requirements for safety and performance. Annex I, Section 5 of the MDR requires, among other things, reducing risks caused by use errors.
Relevance for human factors
The device class does not determine how much human factors work is required. The FDA guidance “Content of Human Factors Information in Medical Device Marketing Submissions” has been final since May 2026 and, according to the FDA, applies to 510(k), De Novo, PMA, and HDE submissions (as of October 2026). It describes a risk-based approach. The assignment of a submission to one of the three HF Submission Categories follows decision points such as changes to the device, the critical tasks from the use-related risk analysis (URRA), the history of the user interface, its complexity, and the existing risk controls. The device class does not appear in these decision points. The FDA also recommends keeping human factors information on hand independently of a submission. The FDA human factors guidance provides the basics.
The class acts indirectly. It determines the pathway and thus which documents the FDA reviews. In addition, the requirements for design and development and design controls (Section 7.3 of ISO 13485) apply under 21 CFR 820.10(c) to manufacturers of Class II, Class III, and certain Class I devices, namely software-automated devices and five types listed in the regulation (see QMSR and Design Controls). For most Class I devices, these requirements therefore do not apply. What IEC 62366-1 requires for the usability engineering process is independent of this.
Two points related to users deserve attention. First, the intended user group influences classification: if a device is intended for lay users instead of professionals, a 510(k) may become necessary despite an exemption under 21 CFR 880.9. Second, the class depends on the Indications for Use. Anyone who changes them later, for example for a different intended user, should review the classification again.
The FDA assigns medical devices to Class I, II, or III under Section 513 of the FD&C Act. According to the FDA, Class I has the lowest risk and Class III the highest. The class determines the controls: General Controls for all, Special Controls in addition for Class II, Premarket Approval for Class III.
The class usually determines the pathway: 510(k) for non-exempt Class I and II devices, PMA for Class III, De Novo for new low to moderate risk devices without a predicate device. Exemptions and their limits are set out in the classification regulations.
The device class does not determine the human factors effort. The FDA guidance on the content of human factors information follows a risk-based approach built on critical tasks, not on the class.
Frequently asked questions (FAQ)
Which classes does the FDA have?
The FDA has three classes. According to the FDA, Class I covers devices with the lowest risk and Class III those with the highest. The basis is Section 513 of the FD&C Act. Among other things, the class determines the applicable controls and the type of submission before the device is placed on the market.
What is the difference between General Controls and Special Controls?
General Controls apply in principle to all medical devices unless an exemption exists, for example registration, listing, and reporting of adverse events. Special Controls are added for Class II when General Controls alone are not sufficient. Examples are performance standards, performance testing, and patient registries.
Does every Class I or II device need a 510(k)?
No. Class I devices generally do not need a 510(k) by law, and the FDA maintains lists of Class II types that are exempt. The exemption has limits, which are set out in the respective part of the classification regulations. For example, a 510(k) is still required if a device is newly intended for lay use.
How do I find the class of my device?
The FDA points to its Product Classification Database and to the classification regulations in 21 CFR Parts 862 to 892. If the classification is unclear, the manufacturer can file a Section 513(g) request, which is subject to a fee. The classification depends on the intended use and the Indications for Use.
Does FDA Class II correspond to MDR Class IIa or IIb?
That cannot be said across the board. The MDR classifies into Classes I, IIa, IIb, and III under 22 rules in Annex VIII, while the FDA classifies into Classes I to III under classification regulations per device type. This article does not give a documented conversion.
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More about our usability engineeringSources
- FDA Guidance: Content of Human Factors Information in Medical Device Marketing Submissions
- 21 CFR Part 820, Quality Management System Regulation (QMSR)
- Regulation (EU) 2017/745 on medical devices (MDR)
- IEC 62366-1:2015+AMD1:2020, Medical devices, Part 1: Application of usability engineering to medical devices
- ISO 13485:2016, Medical devices, Quality management systems, Requirements for regulatory purposes
- Federal Food, Drug, and Cosmetic Act, Section 513 (21 U.S.C. 360c), Classification of devices intended for human use
- Federal Food, Drug, and Cosmetic Act, Section 510 (21 U.S.C. 360), subsections (k) and (n)
- 21 CFR Part 860, Medical Device Classification Procedures
- 21 CFR 880.9, Limitations of exemptions from section 510(k) (General Hospital and Personal Use Devices)
- FDA: Classify Your Medical Device
- FDA: Regulatory Controls
- FDA: Product Classification Database
- FDA CDRH Town Hall, Content of Human Factors Information in Medical Device Marketing Submissions (July 22, 2026)