> For the complete documentation index, see [llms.txt](https://knowledge.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.illumina.com/instrumentation/nextseq-500-550/instrumentation-nextseq-500-550-faq-list/000002584.md).
# At which cycle of NextSeq 500/550 are run metrics calculated?
The following diagram contains information on calculations made during the first 25 cycles during a NextSeq 500/550 run:
* When is the final cluster density calculated?
* When does template generation complete?
* When is phasing/prephasing calculated?
* When is clusters passing filter percentage determined?
* When is base calling determined?
* When is Q30 calculated (quality scoring)?
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| *For any feedback or questions regarding this article (Illumina Knowledge Article #2584), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000002584%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |
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