Buyer guide
ISO 7 and ISO 8 cleanroom requirements
ISO 14644-1:2015 allows up to 352,000 particles of 0.5 µm or larger per cubic metre in an ISO 7 room, and up to 3,520,000 in an ISO 8 room. The standard sets limits only, so air volume comes from your room size, people, process and pressure plan, not from the class alone.
By ZY Cleanroom · Updated · Sources at the end of the page
Particle limits for ISO 7 and ISO 8
ISO 14644-1 classifies air by the number of particles in one cubic metre. The limits are cumulative, so a count at 0.5 µm includes every particle at or above 0.5 µm.
Source: ISO 14644-1:2015, Table 1, published 9 December 2015. The table lists no limits at 0.1, 0.2 or 0.3 µm for these two classes.
| Particle size | ISO 7, particles per m³ | ISO 8, particles per m³ |
|---|---|---|
| 0.5 µm and larger | 352,000 | 3,520,000 |
| 1 µm and larger | 83,200 | 832,000 |
| 5 µm and larger | 2,930 | 29,300 |
State the occupancy state
A class needs an occupancy state. ISO 14644-1 lets you specify a class in any of three. As-built means services running, with no production equipment, materials or people. At rest means equipment installed and running as agreed, with no people. Operational means equipment running with the agreed number of people at work.
Write the state next to each class in your room list. ISO 7 at rest and ISO 7 operational are different targets, and the second is harder to hold.
What drives air volume
ISO 14644-1 contains no air change rate. These factors set the supply air volume.
| Driver | Why it matters |
|---|---|
| Occupancy state | Holding a class with people and equipment working takes more air than holding it at rest. |
| People and process | Air dilutes and removes particles made inside the room. More people or dirtier equipment need more air. |
| Room volume and layout | Airflow paths, return positions and obstacles decide how well supply air sweeps the room. |
| Pressure plan | Air leaks out through gaps and doors to keep neighbouring rooms at lower pressure. Bigger pressure steps and leakier rooms need more air. |
| Heat and humidity load | Equipment heat can set the air volume before particle control does. |
| Recovery target | A shorter clean-up time after a disturbance needs more air. |
Published reference points
Two published reference points exist, both for pharmaceutical work. FDA's 2004 aseptic processing guidance says at least 20 air changes per hour is typically acceptable for ISO 8 supporting rooms, and that significantly higher rates are normally needed for ISO 7 areas. EU GMP Annex 1 (2022) gives a guidance clean-up time of under 20 minutes, and a minimum 10 Pa pressure difference between adjacent rooms of different grades.
Treat these as inputs to a calculation and a test, not as design rules.
Typical uses
ISO 14644-1 does not say which activity needs which class. Your process, your customer and your regulator decide. FDA (2004) recommends at least ISO 7, under dynamic conditions, for the area next to an aseptic processing line. It calls ISO 8 appropriate for less critical work such as equipment cleaning. EU GMP Annex 1 (2022) lists preparation of solutions to be filtered, including sampling and dispensing, as Grade C work. It lists equipment cleaning and handling of cleaned components as Grade D work.
Grade C is ISO 7 at rest and ISO 8 in operation, and Grade D is ISO 8 at rest, so a GMP grade is not one ISO class. For other industries, ask the owner of the specification, such as your customer or product standard, for the class and the state.
Who approves the room
Your regulator, not the contractor, judges whether a facility is acceptable. The contractor builds to your room data sheet and supplies test results. The owner keeps the responsibility.
To have a room list reviewed, send it to ZY Cleanroom, a cleanroom design-and-build contractor with its own panel and door factory in Tianjin, China.
Cleanrooms under ISO 14644: classes ISO 4 to ISO 9 and the parts of the series
ISO 14644 is a series. Part 1 (2015) classifies air cleanliness by particle concentration, Part 2 (2015) covers monitoring to give evidence of cleanroom performance, Part 3 (2019) gives test methods, Part 4 (2022) covers design, construction and start-up, and Part 5 (2025, listed 4 June 2025) covers operations.
Each class step in Part 1 multiplies the limit at 0.5 µm by ten, from 352 particles per m³ at ISO 4 to 35,200,000 at ISO 9. The table follows Table 1 of ISO 14644-1:2015 as reproduced by Beckman Coulter (checked 1 November 2026).
| ISO class | 0.5 µm and larger, particles per m³ | 1 µm and larger, particles per m³ |
|---|---|---|
| ISO 4 | 352 | 83 |
| ISO 5 | 3,520 | 832 |
| ISO 6 | 35,200 | 8,320 |
| ISO 7 | 352,000 | 83,200 |
| ISO 8 | 3,520,000 | 832,000 |
| ISO 9 | 35,200,000 | 8,320,000 |
Questions
Common questions
How many particles does an ISO 7 cleanroom allow?
Up to 352,000 per cubic metre at 0.5 µm and larger, 83,200 at 1 µm and larger, and 2,930 at 5 µm and larger (ISO 14644-1:2015, Table 1).
Is ISO 7 the same as Class 10,000?
FDA's 2004 guidance lists ISO 7 as Class 10,000, which is 352,000 particles of 0.5 µm per cubic metre, and ISO 8 as Class 100,000.
How many air changes per hour does ISO 7 need?
ISO 14644-1 sets none. FDA's 2004 guidance for sterile drug manufacturing says rates significantly higher than 20 are normally needed for Class 10,000 (ISO 7) areas.
Is a Grade C room ISO 7?
At rest, yes: Grade C allows 352,000 particles per cubic metre at 0.5 µm. In operation it allows 3,520,000, the ISO 8 figure (EU GMP Annex 1, 2022, Table 1).
Does an ISO 8 cleanroom require HEPA filters?
ISO 14644-1 sets particle limits and does not name a filter, so the standard itself does not require HEPA. The design still has to show that the room meets the limit in the stated occupancy state. Write the filter grade into the design basis, along with any rule from your regulator or process.
What are the gowning requirements for an ISO 7 cleanroom?
ISO 14644-1 sets no gowning rule, so the owner fixes it in a written procedure based on the process. For GMP rooms, Annex 1 (para 7.13) describes Grade C clothing as covered hair and beards, a single or two-piece trouser suit with a high neck, and disinfected shoes or overshoes. Grade D needs covered hair and beards, a general protective suit, and disinfected shoes or overshoes.
Related guides
- Cleanroom air changes per hour: published values and their limits
- Cleanroom temperature and humidity requirements
- Cleanroom pressure alarm: how to find the cause
- Cleanroom HVAC design: AHU, recirculation and FFU options
- Turnkey cleanroom contractor
- Room list builder
Sources
- ISO 14644-1:2015, Cleanrooms and associated controlled environments, Part 1: Classification of air cleanliness by particle concentration (published 9 December 2015; Table 1 checked 31 October 2026)
- FDA, Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing, Current Good Manufacturing Practice (September 2004, nonbinding; checked 31 October 2026)
- EudraLex Volume 4, Annex 1: Manufacture of Sterile Medicinal Products (published 25 August 2022, applied from 25 August 2023; checked 31 October 2026)
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