# Library quantification and QC for the Illumina miRNA prep kit

**What’s the expected final library yield?**

* There are no official yield expectations for this library type. Final library yields will vary based on the input amount, input quality, and source.

**What is the expected final library size?**

* A miRNA-size library is approximately 200 bp. A piRNA-sized library is approximately 208 bp.
* If there is a peak at approximately 185-192 bp, the peak comprises RNA fragments or small RNAs other than miRNAs. RNA fragments or small RNAs are common in total RNA samples, being particularly strong in biofluid total RNA samples.
* Example Bioanalyzer trace: ![](/files/BAS1Lvdn2hcgfZyi0YRZ)

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #9894), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000009894%20-%20Library%20Preparation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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