In modern clean room operations for precision manufacturing and life sciences, ISO 14644-1 clean room standards, FED-STD-209E classifications, and GMP clean room regulations are the “guardians of quality.” But when engineers talk about a “Class 100 clean room,” the quality team requests “ISO 5,” and auditors review “GMP Grade A” documents, it’s easy to get confused. Don’t worry—this guide will explain the relationship between ISO clean room standards, FED-STD-209E, and GMP clean rooms, so you can confidently manage design, validation, and daily operations.

Why Understanding These Standards Matters

Mixing these terms can be headache-inducing. Think of them as different languages: some people speak American English, some British English, and some “legalese.” Without knowing how they relate, you could make mistakes during design, acceptance, or audits.

In short:

• Practical problem: Engineers say “Class 100,” quality wants ISO, auditors look at GMP. Can they match?
• Historical context: FED-STD-209E is an old US standard, ISO is international, GMP is regulatory. Old and new terms coexist in practice.
• Value of this guide: Quickly build a framework to understand all three, and learn how to choose or convert standards for easier clean room management.

Overview of the Three Major Standards

ISO 14644-1 (International Standard)

ISO 14644-1 is the global standard that tells you “how many particles are allowed in a clean room, and how to measure and test them.”

• Applicable industries: Semiconductors, aerospace, medical devices, pharmaceuticals… virtually any industry that needs contamination control.
• Core value: It’s the “universal language” for designing, constructing, and validating clean rooms—used in contracts, acceptance, and technical communication.

FED-STD-209E (US Historical Standard)

First issued in 1963, FED-STD-209E measured clean room classes in cubic feet. It was officially replaced by ISO standards in 2001.

• Current use: Although obsolete, the “Class X” terminology is still widely used, especially in North American semiconductor projects and legacy facilities.

GMP (Good Manufacturing Practice)

GMP is not just about particle counts—it’s a regulatory framework for pharmaceuticals and medical devices.

• Core content: Controls the full process—from personnel, facilities, and equipment to processes and documentation.
• Environmental requirements: Clean room levels often refer to ISO standards, but GMP emphasizes both dynamic and static conditions, microbial monitoring, and process control.

ISO Classification	Maximum Number of Particles in Air
	(Particles in each cubic meter = or>the specified size)
	>0.1 μm	>0.2 μm	>0.3 μm	>0.5 μm	>1.0 μm	>5.0 μm
ISO 1	10	-	-	-	-	-
ISO 2	100	24	10	-	-	-
ISO 3	1,000	237	102	35	-	-
ISO 4	10,000	2,370	1,020	352	83	-
ISO 5	100,000	23,700	10,200	3,520	832	-
ISO 6	1,000,000	237,000	102,000	35,200	8,320	298
ISO 7	-	-	-	352,000	83,200	2,930
ISO 8	-	-	-	3,520,000	832,000	29,300
ISO 9	-	-	-	35,200,000	8,320,000	293,000

Comparing the Standards

Key differences:

• Unit of measurement: ISO uses cubic meters, FED-STD uses cubic feet (1 m³ ≈ 35.3 ft³).
• State requirements: ISO mainly measures static (empty room), GMP emphasizes both dynamic and static conditions to ensure control throughout production.
• Industry equivalence:

GMP Grade A (dynamic) = ISO 5 = FS209E Class 100

GMP Grade B (static) = ISO 5

GMP Grade B (dynamic) ≈ ISO 7

GMP Grade C (static) = ISO 7 = FS209E Class 10,000

GMP Grade D (static) = ISO 8 = FS209E Class 100,000

Where to Use Each Standard