Data volume

How to estimate the volume of a dataset

1. Consider at least all raw data files. Check if processed data is also required by the journal or the repository that you want to use to publish/store your data.
2. Estimate file size per sample or experiment based on files previously generated using a similar setting.
3. Multiply the estimated file size by the number of samples or experiments you are going to generate during the project.

Formula to estimate the volume of sequencing files (Illumina)

• One .fastq file for Single-End sequencing
  • .fastq MB = Number of million reads x (60 + 2 x read length in bp)
• Paired-End sequencing produces 2 fastq files
  • .fastq MB = Number of million reads x (60 + 2 x read length in bp) x 2

  It is recommended to store .fastq files in a compressed format (ex: .gz), which makes the file approximately 4 times smaller.

Formula to convert Coverage to Number of reads:

• Number of reads needed (Million) = (Coverage x Genome length (bp) / read length) /1000000

If you want to know more about the number of reads needed per experiment, coverage and reads length, see

• Considerations for RNA-Seq read length and coverage
• Recommended Coverage and Read Depth for NGS Applications