The conversions between the firms using Sorenson Genomics and FTDNA have become quite complex with the former's use of ISGF nomenclature. Six markers are involved: DYS441, DYS442, DYS452, DYS463, Y-GATA-10 and Y-GATA-H4.
One way to do the conversions is to go to http://www.smgf.orghttp://www.smgf.org, select the lab where testing was done (from lab), clear all values, enter the values for the six markers and then select the lab that you are converting to (to lab).
Note that FTDNA is not the same as Y-Search. If you are trying to convert results for Y-Search, select Relative Genetics as the to lab and subtract 1 from the resulting value at Y-GATA-H4. The RG values at SMGF follow their old nomenclature.
On 1 Aug 2007, Sorenson Genomics made changes for Ancestry.com for 5 of the 6 markers. On 23 Aug 2007, they added a change for DYS441. DNAHeritage followed suit in Dec 2007.
To go from old RG/old DNAH to Ancestry/current DNAH, add the following to the old RG/DNAH results: DYS441+1 DYS442+5 DYS452+19 DYS463+2 Y-GATA-A10 +2 Y-GATA-A4 +10
To convert from old RG/old DNAH to Y-Search, subtract 1 from Y-GATA-H4.
To convert from Ancestry/current DNAH to Y-Search, subtract the following from your Ancestry/DNAH results: DYS441-1 DYS442-5 DYS452-19 DYS463-2 Y-GATA-A10 -2 Y-GATA-A4 -11
To convert from FTDNA to Y-Search, subtract the following from your FTDNA results: DYS452-19 DYS463-2
To convert from FTDNA's Houston Lab/DNA-Fingerprint to FTDNA, subtract 1 from Y-GATA-H4.
To convert from Ancestry/current DNAH to FTDNA, subtract the following from your Ancestry/DNAH results: DYS441-1 DYS442-5 Y-GATA-A10 -2 Y-GATA-A4 -11