ISO 14644-1 vs EU GMP Grade
Two ways to classify cleanroom air — and how they line up.
What a comparison is not
A comparison is SPEQ’s reading of how two published documents differ. Neither is the right answer, it is not a determination of which applies to you, and neither is summarised in a way that replaces reading it.
ISO 14644-1 classifies cleanrooms by airborne particle concentration into ISO classes (e.g., ISO 5, 7, 8). EU GMP Annex 1 classifies sterile-manufacturing areas into grades A, B, C, and D. The two systems map onto each other, but GMP grades carry extra requirements ISO classification alone does not — the "in operation" vs "at rest" states and microbial monitoring.
| ASPECT | ISO 14644-1 | EU GMP GRADE |
|---|---|---|
| Basis | Airborne particle counts at defined sizes | Particle counts plus microbial and operational requirements |
| Typical mapping (in operation) | ISO 5 · ISO 7 · ISO 8 | Grade A / B ≈ ISO 5; Grade C ≈ ISO 7; Grade D ≈ ISO 8 |
| States | As-built / at-rest / operational (defined by user) | "At rest" and "in operation" both specified |
| Microbial limits | Not part of ISO 14644-1 | Microbial monitoring limits per grade (Annex 1) |
| Scope | Any cleanroom, any industry | Sterile medicinal product manufacture |
| What A/B add | — | Grade A = critical zone; Grade B = background to A, with strict gowning/EM |
Use ISO 14644-1 to classify and certify cleanroom air cleanliness by particle count — the metrological basis used across industries.
Use EU GMP grades for sterile pharmaceutical manufacturing, where the grade carries not just particle limits but microbial monitoring, gowning, and "in operation vs at rest" expectations that ISO classification alone does not.
ISO classes measure particles; GMP grades govern sterile manufacturing. Grade A/B areas correspond to ISO 5 for particles, but a GMP grade is more than an ISO class — it bundles microbial limits, operational states, and behaviour. Design the room to the ISO particle class, but qualify and monitor it to the full GMP grade, including the microbial and in-operation requirements Annex 1 adds.
ISO 14644-1 vs EU GMP Grade: frequently asked questions
Common questions on how ISO 14644-1 and EU GMP Grade differ and when each applies.
How do EU GMP grades map to ISO classes?
In operation, Grade A and Grade B correspond to ISO 5 for particle counts; Grade C corresponds to ISO 7; Grade D corresponds to ISO 8. Grades B/C/D also have distinct "at rest" ISO equivalents. But the GMP grade adds microbial and operational requirements beyond the ISO particle class.
Does ISO 14644 include microbial limits?
No. ISO 14644-1 classifies airborne particle concentration only. Microbial monitoring limits for sterile manufacturing come from EU GMP Annex 1 (and equivalent GMP frameworks), not from the ISO cleanroom-classification standard.
What is the difference between "at rest" and "in operation"?
"At rest" is the cleanroom complete and equipment installed but no personnel present and no production; "in operation" is with personnel working and the process running. Annex 1 specifies limits for both states, because contamination risk is highest in operation.
What makes Grade A special?
Grade A is the critical zone for high-risk operations (e.g., aseptic filling, open product exposure), requiring ISO 5 conditions in operation with unidirectional airflow, and it sits within a Grade B background (for aseptic processing) with stringent gowning and monitoring.