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Hemoglobin in two units: the short answer
To convert hemoglobin from g/dL to mmol/L, multiply by 0.6206. To go back from mmol/L to g/dL, multiply by 1.611 (or divide by 0.6206). For example, 13 g/dL × 0.6206 = 8.1 mmol/L. The converter above works in both directions and shows where the result sits against typical reference ranges.
What the test measures
The Netherlands and a few other places report hemoglobin in mmol/L, while the US uses g/dL and most of Europe g/L. The mmol/L figure is based on the hemoglobin monomer (one heme unit, 16,114 g/mol), so 1 g/dL = 0.6206 mmol/L and 1 mmol/L = 1.611 g/dL.
Why the units differ
Dutch blood donation, pregnancy and anemia guidance is written in mmol/L, so travellers and people comparing results across countries need this conversion. For g/dL ↔ g/L use our separate hemoglobin g/dL to g/L converter.
Where the factor comes from
The conversion factor comes from the molar mass (16,114.5 g/mol (monomer)) and the volume units on each side. Laboratories may round the factor slightly differently, which can change the last digit but never the clinical meaning.
How to convert step by step
- Check the unit printed next to the result on your report – g/dL or mmol/L.
- g/dL → mmol/L: multiply by 0.6206.
- mmol/L → g/dL: multiply by 1.611.
- Round to the same number of decimals your lab uses.
Worked example in reverse: 5.6 mmol/L × 1.611 = 9.0 g/dL.
Hemoglobin conversion chart
| g/dL | mmol/L |
|---|---|
| 7 | 4.3 |
| 8 | 5 |
| 9 | 5.6 |
| 10 | 6.2 |
| 11 | 6.8 |
| 12 | 7.4 |
| 13 | 8.1 |
| 14 | 8.7 |
| 15 | 9.3 |
| 16 | 9.9 |
| 17 | 10.6 |
| 18 | 11.2 |
| mmol/L | g/dL |
|---|---|
| 4.3 | 6.9 |
| 5 | 8.1 |
| 5.6 | 9 |
| 6.2 | 10 |
| 6.8 | 11 |
| 7.4 | 11.9 |
| 8.1 | 13.1 |
| 8.7 | 14 |
| 9.3 | 15 |
| 9.9 | 16 |
| 10.6 | 17.1 |
| 11.2 | 18 |
Hemoglobin levels: what the numbers mean
| Category | g/dL | mmol/L |
|---|---|---|
| Anemia threshold, women (non-pregnant)WHO: <12 g/dL ≈ <7.4 mmol/L | < 12 | < 7.4 |
| Anemia threshold, menWHO: <13 g/dL ≈ <8.1 mmol/L | < 13 | < 8.1 |
WHO hemoglobin thresholds for anemia in adults at sea level. Labs set their own reference ranges.
WHO hemoglobin thresholds for anemia in adults at sea level. Labs set their own reference ranges.
Interpreting hemoglobin results
Hemoglobin carries oxygen in red blood cells. Low hemoglobin (anemia) has many causes, the most common being iron deficiency; others include B12 or folate deficiency, kidney disease, chronic inflammation and blood loss. High hemoglobin can come from dehydration, smoking, living at altitude, testosterone therapy or bone-marrow conditions. Thresholds differ in pregnancy and at altitude.
A single result outside the reference range is common and often not significant on its own. Reference ranges are set so that about 1 in 20 healthy people fall outside them, and every laboratory sets its own limits for its method. Use the range printed on your report and discuss results with the clinician who ordered the test.
When to see a doctor
Contact your clinician if a result is flagged as abnormal and you have symptoms, if a value is far outside the range, or if results are changing over time. This page explains units; it cannot diagnose or replace medical advice.
Frequently asked questions
What is 8.5 mmol/L hemoglobin in g/dL?
8.5 × 1.611 = 13.7 g/dL.
Why do Dutch labs use mmol/L for hemoglobin?
The Netherlands adopted SI molar units for hemoglobin decades ago, counting each heme-containing subunit. It's a convention; the measurement is the same.
Can I use this converter for any lab?
Yes for the unit conversion, which is fixed by chemistry. Reference ranges differ between labs and methods, so compare your converted value with your own lab's range.