featureCounts — RNA-seq Read Counting

Overview

featureCounts (part of the Subread package) assigns sequencing reads in BAM files to genomic features defined in a GTF/GFF annotation. It counts how many reads overlap each gene (or exon, intron, or custom feature), producing a gene × sample count matrix suitable for differential expression analysis with DESeq2 or edgeR. featureCounts processes multiple BAM files in a single command, reporting read assignment statistics (assigned, unassigned by category) alongside the count matrix. It is the standard counting step after STAR alignment in RNA-seq pipelines.

When to Use

• Generating gene-level count matrices from STAR-aligned BAM files for DESeq2 or edgeR
• Counting reads from multiple samples simultaneously in a single featureCounts command
• Handling stranded RNA-seq libraries where sense/antisense assignment matters
• Producing exon-level or custom-feature counts (e.g., for splicing analysis with DEXSeq)
• Verifying strandedness of an RNA-seq library when protocol documentation is unavailable
• Use Salmon instead when no BAM file exists and fast pseudoalignment is preferred
• Use HTSeq-count as an alternative with slower but more flexible counting modes

Prerequisites