Clean Room Classification Calculator
Enter particle counts from your sampling locations. The calculator determines ISO class per ISO 14644-1:2015 using 95% UCL statistics and maps to EU GMP Grades.
Room Preset
Target ISO Class ?
Monitoring State ?
Room Area (m²) ?
Sampling Data (particles/m³)
Location ≥0.5 µm ≥5 µm
Classification Result
ISO 7
≥0.5 µm Analysis
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Mean: -- | SD: -- | UCL: --
≥5 µm Analysis
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Mean: -- | SD: -- | UCL: --
Measured vs ISO Limits

Per-Location Results

Location ≥0.5 µm Status ≥5 µm Status

About Cleanroom Classification per ISO 14644-1

Cleanroom classification determines the maximum permitted concentration of airborne particles in a controlled environment. ISO 14644-1:2015 is the international standard that defines the classification methodology, replacing the older US Federal Standard 209E (which used designations like Class 100, Class 10,000). The standard covers ISO Class 1 (the cleanest, used in semiconductor fabrication) through ISO Class 9 (equivalent to normal room air), though biopharmaceutical manufacturing primarily uses ISO 5 through ISO 8.

The classification formula Cn = 10N × (0.1/D)2.08 calculates the maximum permitted number of particles (Cn) per cubic metre, where N is the ISO class number and D is the particle diameter in micrometres. For the two particle sizes most relevant to pharmaceutical cleanrooms: at ≥0.5 µm, ISO 5 allows 3,520 particles/m³, ISO 6 allows 35,200, ISO 7 allows 352,000, and ISO 8 allows 3,520,000. At ≥5 µm, ISO 5 allows 29, ISO 6 allows 293, ISO 7 allows 2,930, and ISO 8 allows 29,300.

EU GMP Annex 1 maps these ISO classes to pharmaceutical grades: Grade A (aseptic core, ISO 5 at rest and in operation), Grade B (immediate surround of Grade A, ISO 5 at rest / ISO 7 in operation), Grade C (controlled areas, ISO 7 at rest / ISO 8 in operation), and Grade D (surrounding controlled areas, ISO 8 at rest). The 2022 revision of Annex 1 strengthened continuous monitoring requirements and introduced contamination control strategy (CCS) as a mandatory document. This calculator automates the 95% upper confidence limit (UCL) statistical test required by ISO 14644-1 when 2-9 sampling locations are used, eliminating manual spreadsheet calculations and providing instant pass/fail verdicts against both ISO and EU GMP limits.

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Further Reading

Frequently Asked Questions

How do you classify a cleanroom per ISO 14644-1?

ISO 14644-1 classification requires measuring airborne particle concentrations at sampling locations distributed across the cleanroom. The number of sampling locations equals the square root of the room area in m², rounded up (minimum 1). At each location, collect a sample volume large enough to detect at least 20 particles at the class limit. For rooms with 2-9 locations, calculate the 95% upper confidence limit (UCL) of the mean. The room passes if the UCL is at or below the concentration limit for the target ISO class.

What is the 95% UCL calculation for ISO 14644-1?

The 95% upper confidence limit is UCL = mean + t × SD / √N, where N is the number of sampling locations and t is from the Student's t-distribution at 95% confidence with N-1 degrees of freedom. For 1 location, the measured value is used directly. For 2-9 locations, the UCL formula applies. For 10+ locations, the arithmetic mean is sufficient per ISO 14644-1:2015.

How do EU GMP Grades map to ISO cleanroom classes?

Grade A = ISO 5 (at rest and in operation, ≤20 particles ≥5 µm). Grade B = ISO 5 at rest / ISO 7 in operation. Grade C = ISO 7 at rest / ISO 8 in operation. Grade D = ISO 8 at rest (in-operation not defined). The EU GMP limits for Grade A at ≥5 µm (20/m³) are stricter than the ISO 5 formula limit (29/m³).

What are the ISO 14644-1 particle count limits?

The concentration limit formula is Cn = 10N × (0.1/D)2.08. For ≥0.5 µm: ISO 5 = 3,520, ISO 6 = 35,200, ISO 7 = 352,000, ISO 8 = 3,520,000 particles/m³. For ≥5 µm: ISO 5 = 29, ISO 6 = 293, ISO 7 = 2,930, ISO 8 = 29,300 particles/m³. These are also equivalent to FS 209E Class 100, 1,000, 10,000, and 100,000 respectively.

What is the difference between at-rest and in-operation monitoring?

At-rest monitoring measures particle counts when the HVAC is running and equipment is installed but no personnel are present. In-operation monitoring measures counts during normal production. At-rest demonstrates the room's baseline capability; in-operation reflects real manufacturing conditions. EU GMP requires classification in both states, with in-operation limits typically one or two ISO classes higher than at-rest.

How many sampling locations are required?

ISO 14644-1 requires a minimum of ⌈√A⌉ sampling locations, where A is the room area in m². For example: 10 m² needs 4 locations, 25 m² needs 5, 50 m² needs 8, 100 m² needs 10. Locations should be evenly distributed with additional points near HEPA outlets, doorways, and critical workstations.