Which ISO 14644-1 cleanroom class do you need?
The cleanroom class per ISO 14644-1 defines how many particles per cubic metre of air are permitted. This guide explains classes ISO 5 to ISO 8, their particle limits and air change rates, and how they map to GMP grades A to D.
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What do cleanroom classes ISO 5 to ISO 8 mean?
ISO 14644‑1 classifies cleanrooms by the maximum permitted particle concentration per cubic metre of air. The class number is the base-ten logarithm of the allowed particle count: ISO 5 permits at most 3,520 particles of 0.5 µm and larger per m³, while ISO 8 allows 3,520,000, a thousand times more.
The lower the class number, the cleaner the air. Each class has graduated limits for several particle sizes. Measurement uses a particle counter at defined sampling points, either at rest or in operation.
Which class suits which application?
The required class depends on how sensitive the product is. Not every application needs ISO 5. Over-classifying means paying high capital and running costs for air handling that the product does not require.
- ISO 5: aseptic filling, microelectronics, open sterile products.
- ISO 6: assembly of sensitive optics and sensors, medical device core zones.
- ISO 7: medical device packaging, pharma support areas, laboratory zones.
- ISO 8: general manufacturing, gowning rooms, airlocks and prep areas.
How do air change rate and class relate?
The air change rate states how often the room air volume is fully replaced per hour. It keeps particle concentration low by removing generated particles. The stricter the class, the higher the required rate.
ISO 5 usually needs a laminar displacement flow (unidirectional) with full-coverage HEPA or ULPA filters. Lower classes work with turbulent mixing and far fewer air changes, which saves energy.
How do I map GMP grades A to D?
Pharmaceutical production also follows EU GMP Annex 1 with grades A to D. These map approximately to ISO classes but distinguish between at rest and in operation, and additionally require microbiological limits.
Grade A corresponds to ISO 5 both at rest and in operation. Grade B is ISO 5 at rest and ISO 7 in operation. GMP also sets microbial limits such as under 1 CFU per cubic metre for grade A, which ISO 14644‑1 alone does not cover.
Frequently asked questions
What is the difference between at rest and in operation?
At rest measures the empty but ready room without staff, in operation measures during running production with staff and process. Particle counts are higher in operation, so rooms often carry two class values.
Which cleanroom class do I need for medical devices?
Packaging and assembly of non-sterile medical devices usually happens in ISO 7 or ISO 8. Critical core zones or open sterile products require ISO 5 to ISO 6, depending on the risk assessment.
Is a HEPA filter enough for every class?
HEPA filters of class H13 or H14 reliably cover ISO 6 to ISO 8. For ISO 5 with laminar flow and the highest demands, ULPA filters (U15/U16) are sometimes used.
Does grade A automatically equal ISO 5?
Grade A matches ISO 5 for particles both at rest and in operation, but also demands microbiological limits and unidirectional flow. ISO 5 alone does not meet every GMP requirement.
Equip your cleanroom to standard?
We supply filters, garments, meters and equipment to match your cleanroom class per ISO 14644-1 and GMP Annex 1.
Standard-tested
Equipment aligned with ISO 14644-1 and GMP Annex 1.
Right filters
HEPA and ULPA for every cleanroom class.
Measurably clean
Particle counters and documentation for qualification.
Expert advice
Specialists help you choose the right class.