What is fold change? What is logFC?

What is fold change?

Fold change is a metric that expresses the extent of change between two measurements. In gene expression analysis, such as microarray or RNA-Seq analysis, it refers to the ratio of expression between samples or between groups.

What is logFC?

Fold change converted to a logarithmic scale (log fold change, log2 fold change) is sometimes denoted as logFC. In many cases, the base is 2.

Examples of Fold Change / logFC

For example, if the average expression level is 100 in the control group and 200 in the treatment group, the fold change is 2, and the logFC is 1.

Gene NameAverage Expression Level in the Control GroupAverage Expression Level in the Treatment Groupfold changelogFC
Gene A10020021
Gene B10040042
Gene C2001000.5-1

In gene expression analysis, such as microarray or RNA-Seq analysis, figures such as Volcano plots and MA plots are commonly drawn. LogFC corresponds to the x-axis in a Volcano plot and to the y-axis in an MA plot.

Example of a Volcano Plot


Example of an MA Plot


RNA-Seq Data Analysis Software

For those who don't have the time to study analysis methods or lack a high-spec computer necessary for the analysis, please consider using our RNA-Seq data analysis software.


Starting with either raw RNA-Seq data (FASTQ files/public data) or expression tables (CSV/TSV files), users can perform gene expression quantification, identification of differentially expressed genes, gene ontology(GO) analysis, pathway analysis, as well as drawing volcano plots, MA plots, and heatmaps.