CAN FD is the successor of Classical CAN. Most of the OEMs are migrating to CAN FD in the next couple of years. The CiA 601-3 document comes with a spreadsheet to check, whether your selected bit-rates are possible.
CAN FD frames are transmitted with two speeds. The rules for the arbitration bit-rate are the same as for Classical CAN. In the dataphase, the nodes are not synchronized. Therefore, other rules apply such as phase margin for received and transmitted frames. The released document contains all the necessary formulas to calculate the limits. In addition, it proposes, how to measure them. CiA members can download the documents free-of-charge and non-members can purchase them from CiA Office in Nuremberg (Germany).
CAN in Automation – www.can-cia.org