Haemoglobin — g/dL to mmol/L

In short To convert haemoglobin from g/dL to mmol/L, multiply by 0.620559 — so one g/dL is 0.620559 mmol/L, and one mmol/L is 1.61145 g/dL. 12 g/dL is 7.4 mmol/L; 13.5 g/dL is 8.4 mmol/L; 15 g/dL is 9.3 mmol/L. The factor comes from the molar mass, because the conversion uses the haemoglobin monomer, 16114.5 g/mol; that is why it differs for every analyte and why a single "lab unit converter" factor does not exist. Haemoglobin has three reporting conventions, and two of them are only a factor of ten apart: g/dL and g/L. A result of 135 is g/L and the same result is 13.5 in g/dL, which is usually obvious — but mmol/L, used in the Netherlands and parts of Scandinavia, gives 8.4 for the same sample and is genuinely easy to misread. This converts units. It does not interpret results, does not compare your value against a reference interval, and is not a substitute for the clinician who ordered the test — reference intervals differ between laboratories, methods and populations.