# ISO 14644-1 Cleanroom Particle Concentration Limits (Class 1 to 9) > Source: https://netray.co/tools/iso-14644-1-cleanroom-particle-limits-reference > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: Free Tools ## Short answer Maximum allowable particles per cubic metre by ISO class and particle size, plus Fed Std 209E equivalent class names. ## Category electronics ## Industry Semiconductors ## Audience - Cleanroom manager - Facilities engineer - Quality engineer ## Tool **Kind:** worksheet **Mode:** reference **Columns:** #### ISO class **Key:** cls **Type:** text #### 0.1 um **Key:** p01 **Type:** text #### 0.2 um **Key:** p02 **Type:** text #### 0.3 um **Key:** p03 **Type:** text #### 0.5 um **Key:** p05 **Type:** text #### 1 um **Key:** p1 **Type:** text #### 5 um **Key:** p5 **Type:** text #### Fed Std 209E approx. **Key:** fed **Type:** text **Rows:** **Cls:** ISO 1 **P01:** 10 **P02:** 2 **P03:** n/a **P05:** n/a **P1:** n/a **P5:** n/a **Fed:** n/a **Cls:** ISO 2 **P01:** 100 **P02:** 24 **P03:** 10 **P05:** 4 **P1:** n/a **P5:** n/a **Fed:** n/a **Cls:** ISO 3 **P01:** 1,000 **P02:** 237 **P03:** 102 **P05:** 35 **P1:** 8 **P5:** n/a **Fed:** Class 1 **Cls:** ISO 4 **P01:** 10,000 **P02:** 2,370 **P03:** 1,020 **P05:** 352 **P1:** 83 **P5:** n/a **Fed:** Class 10 **Cls:** ISO 5 **P01:** 100,000 **P02:** 23,700 **P03:** 10,200 **P05:** 3,520 **P1:** 832 **P5:** 29 **Fed:** Class 100 **Cls:** ISO 6 **P01:** 1,000,000 **P02:** 237,000 **P03:** 102,000 **P05:** 35,200 **P1:** 8,320 **P5:** 293 **Fed:** Class 1,000 **Cls:** ISO 7 **P01:** n/a **P02:** n/a **P03:** n/a **P05:** 352,000 **P1:** 83,200 **P5:** 2,930 **Fed:** Class 10,000 **Cls:** ISO 8 **P01:** n/a **P02:** n/a **P03:** n/a **P05:** 3,520,000 **P1:** 832,000 **P5:** 29,300 **Fed:** Class 100,000 **Cls:** ISO 9 **P01:** n/a **P02:** n/a **P03:** n/a **P05:** 35,200,000 **P1:** 8,320,000 **P5:** 293,000 **Fed:** n/a **Notes:** Values are maximum permitted concentrations in particles per cubic metre of air, as commonly tabulated from ISO 14644-1 (2015 edition). Fed Std 209E was withdrawn in 2001 but its class names are still widely used. n/a means the class is not defined at that size. Confirm limits against the current licensed standard before using them in a procedure or audit response. ## Content **Intro:** This table lists maximum airborne particle concentrations per cubic metre for each ISO 14644-1 cleanroom class at the standard particle sizes, with the old Federal Standard 209E names beside them. It answers the common questions: what is ISO 5 equal to, and how many 0.5 um particles are allowed in ISO 7. **Sections:** #### How to use the table **Body:** Find your ISO class in the first column and read across for the particle size you monitor. Most semiconductor fabs count at 0.1 um or 0.5 um depending on the class, and OSATs commonly monitor 0.5 um and 5 um. Use the Fed Std column to translate older drawings and customer requirements into ISO classes. **Bullets:** - Compare your particle counter readings with the limit at the same size - Remember that limits are per cubic metre, counters often report per cubic foot - Note n/a entries are undefined, not zero #### How the classes are built **Body:** The classification follows a formula where the limit for each size scales with the class number. Each step in ISO class changes the allowed concentration by a factor of ten, and the limit falls steeply as particles get larger. That is why an ISO 5 area allows 3,520 particles of 0.5 um per cubic metre while ISO 7 allows 352,000. #### Worked example: unit conversion **Body:** A counter reports 85 particles per cubic foot at 0.5 um. One cubic metre is about 35.31 cubic feet, so that is roughly 3,000 particles per cubic metre. This is under the ISO 5 limit of 3,520 for that size. Class determination also needs the sampling plan and statistics from the standard, not a single reading. #### Common mistakes **Body:** Classification is not the same as routine monitoring, and the standard separates the two. Do not compare at-rest results to in-operation limits without stating the occupancy state. Do not cite Fed Std class names in a new specification when an ISO class is available, and always record the sampling location count and volume per location. **Cta:** If your environmental monitoring data sits in spreadsheets or a LIMS, Netray can help build trend queries and alerts on your own infrastructure. **Faq:** #### What ISO class is equal to Class 100? **Answer:** Federal Standard 209E Class 100 corresponds approximately to ISO 5 in ISO 14644-1. The 209E standard was withdrawn in 2001, but the class names remain in common use. #### How many 0.5 um particles are allowed in ISO 7? **Answer:** The limit is 352,000 particles per cubic metre at 0.5 um. ISO 7 corresponds approximately to Fed Std Class 10,000. #### Why are some table cells n/a? **Answer:** The standard does not define a limit for those size and class combinations, because very small particles are not practical to count at high concentration classes. Use the sizes defined for your class. #### Does this table replace the standard? **Answer:** No. It is a convenient reference. Classification and monitoring procedures, sampling locations and statistics are specified in the standard itself, which you should obtain through a licensed source. ## Search terms ISO 14644-1 class limits, iso 5 cleanroom particle count limit, class 100 cleanroom equals iso, cleanroom classification table, fed std 209e to iso conversion, iso 7 vs iso 8 cleanroom, particles per cubic meter by class --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json