The difference between progesterone values ng/ml and nmol/l is that the test results are in different units of concentration. ng/ml, ng refers to nanograms, ml refers to milliliters. nmol/l, nmol refers to nanomoles, l refers to liters, 1l=1000ml. this is the meaning of the progesterone value ng/ml and nmol/l, and the conversion relationship between the two is: ng/ml x 3.18 = nmol/l. Each hospital is different, the progesterone value results show the unit has some differences, some hospitals use ng/ml, some hospitals use nmol / l. As long as the reference value against the range within the normal range can be.