Units - Godrigos/PCRCalc GitHub Wiki
For a long time concentration units were molarity (M) and normality (N), but they are now obsolete, and should not be used. The abundance of a constituent divided by the total volume of a mixture in the International System of Units is given in mol/m3 (or a related acceptable unit). That is the reason why PCRCalc uses pmol/μL and nmol/μL.
Altough, just for reference:
nmol/μL = mM
pmol/μL = μM