ng/ml to nM

[Filledeneige]

I don't know what nM stands for. I checked a few online converters, but didn't find nM as an option. My 4x day free cortisol lab test is in ng/ml:
5.4
2.4
2.3
0.5

However, the site I am using trying to determine my stage of adrenal insufficiency gives graphs with reference ranges in nM. Here is the link: http://www.chronicfatigue.org/ASI%20Normal.html I would like to know where my levels of cortisol fit within their ranges. Perhaps you could just convert one measurement for me and explain how to do it, and I would then convert the remaining three myself. Also, does nM have another name (equivalent) that is perhaps more widely used? Thank you in advance.