A method to map DNA methylation data from bisulfite sequencing approaches to CpG sites measured with the widely used Illumina methylation bead-array platforms. Correlations and median absolute deviations support the validity of using bisulfite sequencing data in combination with Illumina bead-array methylation data. The methyLiftover utility will enhance the field of epigenomic research by expanding the comparability of DNA methylation data in the absence of the common Illumina 450K methylation data. The methyLiftover tool contains functions to subset and map WGBS and RRBS data to the CpG sites specific to the Illumina 450K array, both individually and as a whole directory, and create merged data sets from two user defined methylation data files (e.g. Illumina 850K annotation).