How to calculate Centimorgan lengths from run lengths in one-to-one dna profile comparison
Try having a look at this link:

http://bochet.gcc.biostat.washington.edu/beagle/genetic_maps/plink.GRCh37.map.zip

If you unzip the file, there is a file for each chromosome (1:22) and then 3 for the x chromosome. The first column of each file details which chromosome the file corresponds to, the 3rd column gives you the cumulative genetic distance in cM and the 4th column gives you the genomic coordinate (position) in bp. 

You can then calculate the distance in cM between two positions from this data by subtracting the cM positions between the two positions you are interested in.