ISO 14644 Cleanroom Classes 1–9 Guide
The easiest thing to get confused about when doing a clean room purification project is the naming convention: some people say "ISO 5", some say "Class 100", pharmaceutical people say "Class C", but in fact, they are all talking about the same thing - how many suspended particles are allowed per cubic meter of air. Remember one sentence: the smaller the number after ISO, the cleaner it is. ISO 1 is the almost dust-free limit, while ISO 9 is the level closest to ordinary indoor environments.
一、9 level limits of ISO 14644-1
The international standard for cleanliness classification is ISO 14644-1, and the current corresponding national standard in China is GB/T 25915.1-2021 (modified to adopt ISO 14644-1:2015). It is divided into 9 levels based on the upper limit of the number of particles larger than or equal to a certain particle size per cubic meter of air.
The following table is the original standard table (2015 version), with particle size in the horizontal direction and grade in the vertical direction, measured in units of "pieces/cubic meter":
| Class | ≥0.1μm | ≥0.2μm | ≥0.3μm | ≥0.5μm | ≥1μm | ≥5μm |
|---|---|---|---|---|---|---|
| ISO 1 | 10 | — | — | — | — | — |
| ISO 2 | 100 | 24 | 10 | — | — | — |
| ISO 3 | 1,000 | 237 | 102 | 35 | — | — |
| ISO 4 | 10,000 | 2,370 | 1,020 | 352 | — | — |
| ISO 5 | 100,000 | 23,700 | 10,200 | 3,520 | 832 | — |
| ISO 6 | 1,000,000 | 237,000 | 102,000 | 35,200 | 8,320 | — |
| 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 |
Note: Values represent maximum allowable concentration of airborne particles per cubic meter, ISO14644‑1 Cleanroom Standard.
The "-" in the table is not missing, but according to the standard, cells with particle concentrations that are too low or too high cannot be accurately measured and will not be used as grading criteria. So the most commonly used column in practice is the ≥ 0.5 μ m column - the vast majority of industries classify according to this column. For example, ISO 5, which is most commonly asked, requires no more than 3520 particles of ≥ 0.5 μ m per cubic meter of air. For each level decrease, multiply this number by 10: ISO 6 is 35200, ISO 7 is 352000, and ISO 8 is 3520000.
二、How do ISO levels correspond to "hundred level, thousand level, ten thousand level"
'Level 100, Level 1000, Level 10000' is the customary term for the old American standard (FS209E). This standard was abolished in 2001, but its name is still used in China today. The comparison relationship is as follows:
| Cleanliness Name | US Federal FS209E | ISO 14644-1 | ≥0.5μm Limit (pc/m³) |
|---|---|---|---|
| Class 100 | Class 100 | ISO 5 | 3,520 |
| Class 1,000 | Class 1,000 | ISO 6 | 35,200 |
| Class 10,000 | Class 10,000 | ISO 7 | 352,000 |
| Class 100,000 | Class 100,000 | ISO 8 | 3,520,000 |
| Class 1,000,000 | Class 1,000,000 | ISO 9 | 35,200,000 |
Note: The table shows common cleanroom cleanliness classifications according to US Federal Standard 209E and ISO 14644-1, with particle concentration limits for particles ≥0.5μm.So, "Class 100=ISO 5", "Class 10000=ISO 7", "Class 100000=ISO 8", remember that these three groups are basically sufficient.
三、How do ISO grades correspond to GMP A/B/C/D
The pharmaceutical industry does not mention ISO levels, but rather A/B/C/D. It corresponds to ISO levels in two states: static and dynamic
| GMP Class | At‑rest | In‑operation |
|---|---|---|
| Grade A | ISO 5 | ISO 5 |
| Grade B | ISO 5 | ISO 7 |
| Grade C | ISO 7 | ISO 8 |
| Grade D | ISO 8 | Not specified |
Note: EU GMP cleanroom classification comparison for at‑rest and in‑operation conditions.
A-level is the highest requirement (core area for filling and aseptic operations), which must meet ISO 5 both statically and dynamically; The lowest level is D, and a static level of ISO 8 (100000 level) is sufficient.
四、Where are common levels used
| Cleanliness Class | Typical Applications |
|---|---|
| ISO 5 (Class 100) | Sterile drug filling, semiconductor lithography |
| ISO 6 (Class 1,000) | Semiconductor manufacturing, precision optics |
| ISO 7 (Class 10,000) | GMP Grade C sterile preparation, implantable medical devices, precision electronics |
| ISO 8 (Class 100,000) | Food, cosmetics, general medical devices, GMP Grade D |
Note: Typical cleanroom applications by ISO 14644-1 cleanliness class.
The basic principle of selection is to meet the minimum level of process and regulatory requirements. The higher the level, the more expensive the construction and operation costs, not necessarily the higher the better.
The higher the level, the more prestigious it is, but it is just enough according to your product and regulations. I'm not sure how to determine the level. You can leave a message saying your industry and product, and I'll help you determine which level to achieve.