Cleanroom Standards Comprehensive Guide 2026

ISO 14644 Standards

ISO 14644 defines cleanroom classifications ranging from ISO1 to ISO 9, including ISO1, ISO2, ISO3, ISO4, ISO5, ISO6, ISO7, ISO8, and ISO9.

ISO Class 1 represents the cleanest environment, while ISO Class 9 is the least clean. However, even though ISO 9 is classified as the “dirtiest” level, an ISO 9 cleanroom is still significantly cleaner than a typical indoor environment.

Federal Standard 209 (FS 209E)

The former Federal Standard 209E (FS 209E) defined cleanroom classes as Class 100,000, 10,000, 1,000, 100, 10, and 1. This standard was officially replaced by ISO 14644-1 in 1999 and formally withdrawn in 2001, although it is still widely referenced in practice.

U.S. Food and Drug Administration (FDA) Cleanroom Standards

In addition to general cleanroom classifications, cleanrooms must also comply with industry-specific and international regulations. For example, EU GMP (Grades A, B, C, and D) applies to pharmaceutical manufacturing, while USP <795>, <797>, and <800> are relevant to pharmaceutical compounding facilities.

ISO Class 5 Cleanroom (Class 100 Cleanroom)

In an ISO Class 5 cleanroom, filtered air sweeps across the room in a unidirectional airflow pattern, typically at a velocity of 0.3 to 0.5 m/s, and is exhausted through the floor. This airflow design continuously removes airborne contaminants from the space.

Cleanrooms with unidirectional airflow are more expensive than non-unidirectional designs, but they are capable of meeting stricter cleanliness classifications, such as ISO Class 5 or higher.

Air Changes per Hour (ACH):

ISO 5 areas: 240–360 air changes per hour

ISO 6 areas: 90–180 air changes per hour

ISO 7 areas: 30–60 air changes per hour

ISO 8 areas: 15–25 air changes per hour (anteroom)

Some of Our Previous ISO Class 5 Cleanroom Projects:

ISO Class 5 nanomanufacturing cleanroom facility

ISO Class 6 Cleanroom (Class 1,000 Cleanroom)

In principle, to achieve ISO Class 6 air cleanliness throughout the entire space, personnel and materials should enter the cleanroom sequentially through ISO Class 8 (anteroom), then ISO Class 7, and finally into the ISO Class 6 area, as illustrated.

Air Changes per Hour (ACH):

ISO 6 areas: 90–180 air changes per hour

ISO 7 areas: 30–60 air changes per hour

ISO 8 areas: 15–25 air changes per hour (antechamber)

Some of Our Previous ISO Class 6 Cleanroom Projects:

Semiconductor ISO Class 6 cleanroom

Electronics Manufacturing Services (EMS) cleanroom (ISO Class 6)

ISO Class 6 cell production cleanroom for animal laboratories

ISO Class 7 Cleanroom (Class 10,000 Cleanroom)

ISO Class 7 is one of the most commonly used cleanroom classifications. If an ISO Class 7 cleanroom is required, it is recommended to install an ISO Class 8 airlock or changing room before entering the ISO 7 space. The two areas operate with different air change rates, as outlined below.

Air Changes per Hour (ACH):

ISO 7 areas: 30–60 air changes per hour

ISO 8 areas: 15–25 air changes per hour (anteroom)

These cleanrooms typically use non-unidirectional airflow.

Some of Our Previous ISO Class 7 Cleanroom Projects:

ISO Class 7 cleanroom for electronic component manufacturing

ISO Class 7 cleanroom for the health supplement industry

ISO Class 8 Cleanroom (Class 100,000 Cleanroom)

If an adjacent unclassified area (such as an office or laboratory) corresponds to ISO Class 9, personnel may enter an ISO Class 8 cleanroom directly without an airlock. However, depending on the production process carried out inside the cleanroom, a changing room or gowning area may still be required.

Air Changes per Hour (ACH):

ISO 8 areas: 15–25 air changes per hour

Some of Our Previous ISO Class 8 Cleanroom Projects:

ISO Class 8 cleanroom for pharmaceutical manufacturing

Cleanroom facilities for the pharmaceutical industry

Cleanroom wall extensions for medical technology manufacturers

ISO Class 8 cleanroom for medical device manufacturing

ISO Class 8 cleanroom for the automotive industry

Airborne Particle Cleanliness Levels (per Cubic Meter)

What Is Cleanroom Classification?

Cleanroom classification follows standards established by organizations such as the ISO (International Organization for Standardization). Classifications (such as ISO Class 1 through ISO Class 9) specify the maximum allowable number of airborne particles per cubic meter of air at defined particle sizes (for example, 0.5 microns).

A lower class number (such as ISO Class 1) indicates a cleaner environment with fewer airborne particles, while higher class numbers allow progressively higher particle concentrations.

What Are the Cleanroom Classifications?

ISO 14644-1:

ISO Class 1, 2, 3, 4, 5, 6, 7, 8, and 9

Federal Standard 209E (FS 209E):

Class 1, 10, 100, 1,000, 10,000, and 100,000

How Does the FDA Classify Cleanrooms?

Grade A clean areas:

Airborne particle levels correspond to ISO Class 5, with limits applied to particles ≥5.0 μm.

Grade B clean areas:

Airborne particle cleanliness corresponds to ISO Class 6, covering particles ≥0.5 μm and ≥5.0 μm.

Grade C clean areas:

Airborne particle levels are classified as ISO Class 7 under both at-rest and operational conditions.

Grade D clean areas:

Airborne particle levels correspond to ISO Class 8 under at-rest conditions.

What Is an ISO Class 7 or ISO Class 8 Cleanroom?

ISO Class 7 cleanroom:

The maximum allowable concentration of airborne particles ≥0.5 μm is 352,000 particles per cubic meter of air.

ISO Class 8 cleanroom:

The maximum allowable concentration of airborne particles ≥0.5 μm is 3,520,000 particles per cubic meter of air.

What Is a Class 1,000 Cleanroom?

According to Federal Standard 209E (FS 209E), a Class 1,000 cleanroom is an environment controlled to maintain acceptable levels of airborne particles. For particles 0.5 microns (μm) or larger, the maximum allowable concentration is 1,000 particles per cubic foot (approximately 35,300 particles per cubic meter).

What Is a Class 10 Cleanroom?

According to Federal Standard 209E (FS 209E), a Class 10 cleanroom is an environment controlled to maintain very low levels of airborne particles. For particles 0.5 microns (μm) or larger, the maximum allowable concentration is 10 particles per cubic foot (approximately 353 particles per cubic meter).

What Is the ISO 6 Standard?

Key specifications for an ISO Class 6 cleanroom:

For particles 0.5 microns (μm) or larger: maximum 1,000,000 particles per cubic meter (approximately 35,300 particles per cubic foot)

 For particles 5.0 microns (μm) or larger: maximum 29,300 particles per cubic meter (approximately 1,000 particles per cubic foot)

 ISO Class 6 defines a controlled cleanroom environment with specific limits on airborne particulate contamination. It provides guidance for industries that require a controlled environment but do not need the stricter cleanliness of ISO Class 5 or higher.

What Is ISO 14644 Cleanroom Classification?

ISO 14644 is an international standard that provides guidance for cleanrooms and controlled environments. It includes a series of standards that classify air cleanliness based on the concentration of airborne particulate contamination.

The classification ranges from ISO Class 1 (the cleanest) to ISO Class 9 (the least clean).

What Are GMP Grade A and B Cleanroom Environments?

 Grade A:

In a static environment, the maximum allowable airborne particles per cubic meter are:

 ≥0.5 μm: 3,520 particles

 ≥5.0 μm: 20 particles

The requirements in a dynamic environment are the same as in the static environment.

 Grade B:

In a static environment, which is adjacent to a Grade A area, the maximum allowable airborne particles per cubic meter are:

 ≥0.5 μm: 3,520 particles

 ≥5.0 μm: 29 particles

 In a dynamic environment, the limits are higher:

 ≥0.5 μm: 352,000 particles

 ≥5.0 μm: 2,900 particles

What Are ISO 14644 Cleanroom Classes?

Both ISO (International Organization for Standardization) and GMP (Good Manufacturing Practice) provide important frameworks for defining modular cleanroom standards, but they serve different purposes, focusing on different aspects of cleanroom management and operation.

The Role of HEPA Filters in Cleanroom Standards

HEPA filters can capture 99.97% of airborne particles ≥0.3 microns, significantly improving cleanroom cleanliness and ensuring a highly controlled, contamination-free environment. Their use is critical for meeting the stringent air quality requirements necessary in industries such as pharmaceuticals, biotechnology, and electronics manufacturing.