# What is the Number of Samples Locations Calculations Readings for ISO14644?

> The number of sample locations required to verify compliance with ISO 14644-1 (Air Cleanliness Classification by Particle Concentration) is determined by the size of the cleanroom or controlled area. ISO 14644 specifies a formula and provides tables to calculate the number of sampling locations based on the room’s area.

- Author: Ashraf Almuhtaseb (Data Center Cleaning Specialist)
- Published: 2026-06-06
- Updated: 2026-09-29
- URL: https://wurriors.com/en/articles/what-is-the-number-of-samples-locations-calculations-readings-for-iso14644-370

**What is the Number of Samples Locations Calculations Readings for ISO14644?**

**By Ashraf Almuhtaseb | Data Center Technical Cleaning Expert |**[**idata.center**](http://idata.center)

The number of sample locations required to verify compliance with ISO 14644-1 (Air Cleanliness Classification by Particle Concentration) is determined by the size of the cleanroom or controlled area. ISO 14644 specifies a formula and provides tables to calculate the number of sampling locations based on the room’s area.

**Calculation for the Number of Sample Locations**

The number of sample locations is calculated using the formula:

𝑁𝐿=27× (𝐴 𝑚² ÷ 1000)

Where:

**NL** = Number of sample locations (rounded up to the next whole number)

**A** = Area of the cleanroom or zone in square meters (m²)

**Simplified Table of Sample Locations**

Below is a quick reference for typical cleanroom sizes:

**Room Area (m²)**

**Minimum Sample Locations**

2𝑚² = 2 readings

4𝑚² = 2 readings

10𝑚² = 3 readings

20𝑚² = 5 readings

50𝑚² = 8 readings

100𝑚² = 10 readings

500𝑚² = 23 readings

1000𝑚² = 32 readings

Larger than 1000 𝑚² = Use this formula (𝑁𝐿=27× (𝐴 𝑚² ÷ 1000) )

This table is a suggested number of samples per area; you can take more samples than suggested, and taking fewer is not recommended.

**Sampling Procedure**

**A- Particle Measurement**:

Measure particle concentration at each sampling location for the required particle sizes (e.g., 0.1 µm, 0.5 µm).

Use particle counters that comply with ISO 21501-4 standards.

**B- Duration of Sampling:**

The volume of air sampled at each location must be sufficient to detect the required number of particles based on the cleanroom classification.

**C- Uniform Distribution:**

Sampling points should be evenly distributed across the room, avoiding clustered locations unless local contamination sources are expected.

**About the Author**

Ashraf Almuhtaseb is a Data Center Technical Cleaning Expert with over 9 years of specialized experience since 2017. He is the only independent professional in the MENA region — and one of very few globally — publishing dedicated, in-depth technical knowledge on data center cleaning standards, contamination control, and ISO 14644 compliance. Visit [idata.center](http://idata.center) for more articles, guides, and resources.

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*© Ashraf Almuhtaseb |*[*idata.center*](http://idata.center)*| All rights reserved*

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Ashraf Almuhtaseb is a Data Center Technical Cleaning Expert with over 9 years of specialized field experience since 2017, and the only independent professional in the MENA region publishing dedicated technical content on data center cleaning, contamination control, and ISO 14644 compliance.

© 2026 Ashraf Almuhtaseb — https://wurriors.com/