Hemoglobin Unit Converter
Hemoglobin lab test units are not the same everywhere. Enter the number on your report, pick the unit it is printed in, and convert hemoglobin g/dL to mmol/L or g/L — with the same value shown in all three units and the standard adult reference ranges beside it.
Converted value
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Converted value
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- Grams per deciliter
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- Grams per liter
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- Millimoles per liter
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Reference ranges
- Adult men
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- Adult women
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Adult ranges from Mayo Clinic Laboratories, shown for reference. Ranges differ by laboratory, by age and in pregnancy — read your value against the range printed on your own report, and leave the interpretation to a clinician who has the full blood count and your history.
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Why hemoglobin units differ by country
A hemoglobin lab test measures one thing — how much hemoglobin is carried in a given volume of blood — but reports it on different scales. Labs in the United States use conventional mass units, grams per deciliter (g/dL). Many labs elsewhere use grams per liter (g/L), and labs that follow SI reporting use millimoles per liter (mmol/L), a molar concentration. A result of 13.5 g/dL, 135 g/L and 8.38 mmol/L are the same measurement written three ways.
Mass units convert by moving the decimal point: 1 g/dL is 10 g/L. Going to a molar unit needs the molecular weight of hemoglobin, 16,114 g/mol for a single monomer, which gives 1 g/dL = 0.6206 mmol/L. To convert hemoglobin g/dL to mmol/L, multiply by 0.6206; to go back, divide by it. A few sources quote molar concentration on a four-monomer tetramer basis instead, which prints a number four times smaller — this converter follows the monomer convention used in clinical reporting.
For orientation, Mayo Clinic Laboratories quotes adult reference ranges of 13.2–16.6 g/dL for men and 11.6–15.0 g/dL for women. Those numbers are reference information, not a threshold to act on. Ranges are set by each laboratory and differ by analyzer, by age and in pregnancy, so the range printed on your own report is the one that belongs with your result.
g/L = g/dL × 10 · mmol/L = g/dL × 0.6206 · g/dL = mmol/L ÷ 0.6206 This tool converts units on a result you already have. It does not interpret that result and it is not a diagnosis. A hemoglobin value is read by a clinician alongside the rest of the blood count, any other tests ordered with it, and your own medical history — a single number out of that context does not describe a condition.
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Hemoglobin lab test units FAQ
Why do US labs report hemoglobin in g/dL and European labs in mmol/L?
US labs report in conventional mass units, where concentration is grams of hemoglobin per deciliter of blood. SI reporting, adopted widely in Europe, expresses the same concentration in moles per liter instead, which is why the number looks so different. Neither is more accurate — they are two scales for one measurement, and g/L sits between them as a mass unit on a per-liter basis.
How do I convert hemoglobin from g/dL to mmol/L?
Multiply the g/dL figure by 0.6206, the factor that comes from the hemoglobin monomer molecular weight of 16,114 g/mol. To convert back, divide the mmol/L figure by 0.6206. For g/L, multiply g/dL by 10. So 13.5 g/dL is 135 g/L and about 8.38 mmol/L.
What is the standard adult reference range for hemoglobin?
Mayo Clinic Laboratories quotes 13.2–16.6 g/dL for adult men and 11.6–15.0 g/dL for adult women. In other units that is 132–166 g/L and 8.19–10.30 mmol/L for men, 116–150 g/L and 7.20–9.31 mmol/L for women. This converter shows where an entered value sits relative to those numbers as reference information only; what a result means is for a clinician to say, with the full panel and your history in front of them.
Is the hemoglobin reference range different for men and women?
Yes. Published adult ranges are reported separately for men and women, and the quoted range for women sits lower and wider than the one for men. Laboratories also publish separate ranges for children by age, and pregnancy is handled separately again, so the correct range depends on who the report belongs to.
Why does the range on my own report differ from the one shown here?
Reference ranges are set by each laboratory from its own analyzer and the population it serves, so they shift between labs and are also affected by age, pregnancy and altitude. Use the range printed next to your result, and take any question about that result to the clinician who ordered the test.