# RTA4 Q Score Bin Ranges on the NovaSeq X/X Plus

**Background**

The NovaSeq X/X Plus utilizes Real Time Analysis v4 (RTA4) for base calling and quality scoring. There are three Q score bins used on the NovaSeq X/X Plus, and these Q score calls are reported as an average for the range of called scores. Please see below for the relevant Q Score Bins and Ranges depending on Control Software version.

*Control Software v1.3*

<table data-header-hidden><thead><tr><th valign="top"></th><th valign="top"></th></tr></thead><tbody><tr><td valign="top">Bin</td><td valign="top">Q Score Range</td></tr><tr><td valign="top">2</td><td valign="top">NoCall, 0-2</td></tr><tr><td valign="top">9</td><td valign="top">3-17</td></tr><tr><td valign="top">24</td><td valign="top">18-29</td></tr><tr><td valign="top">40</td><td valign="top">30+</td></tr></tbody></table>

*Control Software v1.2 and v1.2.2*

<table data-header-hidden><thead><tr><th valign="top"></th><th valign="top"></th></tr></thead><tbody><tr><td valign="top">Bin</td><td valign="top">Q Score Range</td></tr><tr><td valign="top">2</td><td valign="top">NoCall, 0-2</td></tr><tr><td valign="top">12</td><td valign="top">3-17</td></tr><tr><td valign="top">24</td><td valign="top">18-29</td></tr><tr><td valign="top">40</td><td valign="top">30+</td></tr></tbody></table>

For more information on changes to Q Score bins with Control Software v1.2, please see the following Illumina article:

[NovaSeq X v1.2 software enables sequencing with 80% of bases >= Q40](https://www.illumina.com/science/genomics-research/articles/data-quality-q-scores.html)

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