# Run folder sizes and disk space on the NextSeq 500/550
All run folder sizes listed below are only to be used for approximation. Folder sizes will vary depending on the raw cluster density and the number of clusters passing filter for a run.
* The examples below are based on dual-indexing runs with optimal clustering and clusters passing filter greater than 80%.
* The following also include FASTQ files generated on the instrument by the Local Run Manager FASTQ workflow (NextSeq Control Software v4.0 and higher).
**Notes:**
* The NextSeq 500/550 hard drive is 1770 GB total.
* 498 GB are partitioned to C:\ for the Operating System Files and Illumina software Installation.
* The remaining 1272 GB are allocated to D:, where run data is stored.
For further information on other Illumina instruments, search for Knowledge Base article **Approximate sizes of sequencing run output folders.**
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