📊 “We need an ISO 7 cleanroom.” What does that number actually mean? Cleanroom classes aren’t a vague rating — they’re a precise limit on how many airborne particles are allowed in a cubic metre of air. Get the class right and you control contamination; get it wrong and you either fail audits or overspend on a room cleaner than you need.
Here’s what the ISO 14644-1 classes mean, how to read them, and which class fits which job. 👇
🔢 What a cleanroom “class” really measures
The standard is ISO 14644-1. It defines nine classes — ISO 1 (cleanest) to ISO 9 (dirtiest) — based on the maximum number of particles, at given sizes, allowed per cubic metre of air.
📋 The ISO 14644 classes at a glance
The most-referenced figure is the limit for particles ≥ 0.5 micron:
| ISO Class | Max particles ≥0.5µm per m³ | Old US (FED-STD-209E) | Typical use |
|---|---|---|---|
| ISO 3 | 35 | Class 1 | Semiconductor photolithography |
| ISO 4 | 352 | Class 10 | Advanced semiconductor fabs |
| ISO 5 | 3,520 | Class 100 | Aseptic pharma filling, semiconductor |
| ISO 6 | 35,200 | Class 1,000 | Medical devices, precision optics |
| ISO 7 | 352,000 | Class 10,000 | Electronics assembly, pharma support |
| ISO 8 | 3,520,000 | Class 100,000 | General cleanrooms, packaging |
ISO 1 and ISO 2 are rarer, ultra-clean classes measured at smaller particle sizes (≥0.1µm). Limits shown are from ISO 14644-1:2015.
🏭 Which class do you actually need?
- 🔬 Semiconductor fabs → ISO 3–5 (photolithography is the strictest)
- 💊 Sterile / aseptic pharma → ISO 5 at the point of fill, inside an ISO 7 surrounding
- 🩺 Medical device manufacturing → typically ISO 7–8
- 💡 Electronics & PCB assembly → ISO 7–8, often with ESD control
- 📦 Packaging / general controlled areas → ISO 8
⏱️ The detail auditors check: occupancy state
A cleanroom’s particle count is measured in one of three states — and the class only means something if you state which:
🏗️ As-built
Empty room, systems running, no equipment or people.
⚙️ At-rest
Equipment installed and running, but no operators present.
👷 Operational
Fully working — equipment running and people present. The toughest state to pass.
🧤 What keeps your room in-class
Maintaining a classification is a daily discipline, not a one-off certification. The everyday products that hold particle counts down:
- 🧤 Cleanroom gloves & garments — contain the particles people shed
- 🧻 Low-lint wipers & cleanroom paper — clean without adding fibres
- 🪑 Cleanroom-rated seating — non-shedding, wipeable, ESD-safe chairs
- 🌀 HEPA/ULPA vacuums — capture sub-micron particles instead of redistributing them
- 🦶 Sticky mats & rollers — stop particles entering at the door
📞 Equipping a cleanroom in Singapore?
Phil Industries supplies the consumables and equipment that keep cleanrooms in-class — ESD & cleanroom gloves, low-lint wipers, sticky mats, cleanroom-rated seating, and HEPA/ULPA vacuums.
📱 WhatsApp: +65 9853 9030
☎️ Tel: +65 6555 1745
✉️ Email: kenneth@phil-industries.com.sg
👉 Browse ESD & cleanroom consumables, cleanroom chairs or cleanroom vacuums.