What is the conversion factor between g/dL and mmol/L?

Hemoglobin in mmol/L = g/dL × 0.6206. Clinical laboratory substance concentration is conventionally reported per monomeric Hb(Fe) subunit (molar mass about 16,114 g/mol, one quarter of the roughly 64,500 g/mol tetramer), giving 1 g/dL ≈ 0.6206 mmol/L.

How does g/dL relate to g/L?

g/L = g/dL × 10. The g/L unit is used in SI-based laboratory systems (common in the UK and many European countries), while g/dL is standard in the US.

How do I convert hemoglobin mmol/L to g/dL?

Divide the mmol/L value by 0.6206 (about the same as multiplying by 1.611). For example, 8.0 mmol/L ÷ 0.6206 = 12.9 g/dL, about 129 g/L. This uses the monomeric Hb(Fe) convention that laboratories reporting mmol/L normally follow.

What is a normal hemoglobin level?

Use the reference interval printed on the laboratory report. Intervals vary with the laboratory and method and may also vary with age, sex, pregnancy, altitude, sample type, and clinical context. This converter does not diagnose anemia or polycythemia.

What hemoglobin level counts as anemia?

The WHO 2024 guideline defines anaemia at sea level as hemoglobin below 130 g/L (13.0 g/dL) in men 15 to 65, below 120 g/L (12.0 g/dL) in non-pregnant women 15 to 65 and children 12 to 14, below 115 g/L in children 5 to 11, below 110 g/L in children 24 to 59 months and in the first and third trimesters of pregnancy, and below 105 g/L in children 6 to 23 months and in the second trimester. Severe anaemia is below 80 g/L for adults and older children and below 70 g/L for young children and pregnancy. Your own laboratory range and your clinician decide what applies to you.

How does altitude change hemoglobin?

People living at elevation have higher hemoglobin, so WHO 2024 subtracts an adjustment from the measured value before comparing it with the cutoff: 4 g/L at 500 to 999 m, 8 g/L at 1,000 to 1,499 m, 11 g/L at 1,500 to 1,999 m, 14 g/L at 2,000 to 2,499 m and up to 33 g/L at 4,500 to 4,999 m. With a known elevation the guideline's equation, 0.0056384 × elevation + 0.0000003 × elevation², is more precise; this tool uses it from 500 m. Smokers get a further 3 to 6 g/L adjustment.

What is the difference between Hb(Fe) and tetramer mmol/L?

Hemoglobin is a tetramer of four subunits, each with one iron atom. Laboratories that report mmol/L, mainly in the Netherlands and Denmark, count subunits (Hb(Fe), about 16,114 g/mol), so 1 g/dL = 0.6206 mmol/L. Counting whole molecules (about 64,458 g/mol) gives four times less: 1 g/dL = 0.1551 mmol/L. A result near 8.5 mmol/L is Hb(Fe); a value near 2.1 mmol/L for the same blood would be tetramer.

Why is hemoglobin measured in mmol/L in some countries?

Some countries that apply the Système International (SI) strictly, mainly the Netherlands and Denmark, report hemoglobin as a substance concentration in mmol/L Hb(Fe). Most other SI countries, including the UK, Canada and Australia, report mass concentration in g/L, and the US uses g/dL.

Is mg/dL the same as g/dL for hemoglobin?

No. Because 1 gram equals 1,000 milligrams, 1 g/dL equals exactly 1,000 mg/dL. The tool also reports mg/L, where 1 g/dL equals exactly 10,000 mg/L.

Hemoglobin Unit Converter

Enter a hemoglobin result to convert it among g/dL, g/L, mmol/L (Hb(Fe) or tetramer), mg/dL and mg/L. Optionally compare it with your report's range or the WHO 2024 anaemia cutoffs adjusted for elevation and smoking.

Hemoglobin in g/dL = g/L ÷ 10, so 121 g/L is 12.1 g/dL.

Enter Hemoglobin Value

Value

Unit

Laboratory reference interval (optional, same unit)

Leave blank for conversion only. Reference intervals differ; copy limits from the same report as your result.

WHO 2024 anaemia check (optional) Population group

Elevation of residence

Smoking

Converted Values

Enter a value above and click Convert.

Hemoglobin Conversion Chart

Common values using the conventional clinical Hb(Fe) factor. Select a value to load it into the converter.

Hemoglobin values from 6 to 18 grams per deciliter converted to grams per liter, millimoles per liter Hb(Fe), and milligrams per liter.
g/L	mmol/L Hb(Fe)	mg/L
60	3.72	60,000
70	4.34	70,000
80	4.96	80,000
90	5.59	90,000
100	6.21	100,000
110	6.83	110,000
120	7.45	120,000
130	8.07	130,000
140	8.69	140,000
150	9.31	150,000
160	9.93	160,000
170	10.55	170,000
180	11.17	180,000

Convention: mmol/L is reported as Hb(Fe), based on the approximately 16,114.5 g/mol hemoglobin subunit convention. It is not the tetramer molar concentration.

Hemoglobin mmol/L to g/dL Chart

For reports in mmol/L Hb(Fe): g/dL = mmol/L ÷ 0.6206.

mmol/L Hb(Fe)	g/dL	g/L
4.0	6.4	64
4.5	7.3	73
5.0	8.1	81
5.5	8.9	89
6.0	9.7	97
6.5	10.5	105
7.0	11.3	113
7.5	12.1	121
8.0	12.9	129
8.5	13.7	137
9.0	14.5	145
9.5	15.3	153
10.0	16.1	161
10.5	16.9	169
11.0	17.7	177

WHO 2024 Hemoglobin Cutoffs for Anaemia

Sea-level values in g/L (divide by 10 for g/dL). Used for population screening and research; a clinician interprets an individual result.

Population	No anaemia	Mild	Moderate	Severe
Children 6–23 months	≥105	95–104	70–94	<70
Children 24–59 months	≥110	100–109	70–99	<70
Children 5–11 years	≥115	110–114	80–109	<80
Children 12–14 years	≥120	110–119	80–109	<80
Non-pregnant women 15–65 years	≥120	110–119	80–109	<80
Men 15–65 years	≥130	110–129	80–109	<80
Pregnancy, first trimester	≥110	100–109	70–99	<70
Pregnancy, second trimester	≥105	95–104	70–94	<70
Pregnancy, third trimester	≥110	100–109	70–99	<70

Adjustments subtracted from measured hemoglobin

Elevation (m)	g/L	Smoking	g/L
Under 500	0	Non-smoker	0
500–999	4	Smoker, amount unknown	3
1,000–1,499	8	Under 10 cigarettes/day	3
1,500–1,999	11	10–19 cigarettes/day	5
2,000–2,499	14	20 or more/day	6
2,500–2,999	18
3,000–3,499	21
3,500–3,999	25
4,000–4,499	29
4,500–4,999	33

Source: WHO Guideline on haemoglobin cutoffs to define anaemia in individuals and populations (2024), Tables 3–5. Elevation band values come from the equation 0.0056384 × m + 0.0000003 × m². Not medical advice.

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Quick answer

Hemoglobin in g/dL = g/L ÷ 10, so 121 g/L is 12.1 g/dL. For mmol/L (Hb(Fe) convention), multiply g/dL by 0.6206, and divide mmol/L by 0.6206 to get back to g/dL.

Examples

g/L	g/dL	mmol/L
80	8.0	4.96
100	10.0	6.21
121	12.1	7.51
135	13.5	8.38
150	15.0	9.31
170	17.0	10.55

Enter your result in any unit to see all five units at once, copy them, or compare with your lab's own range.

Summary

How it works

Enter your hemoglobin value in the input field.
Select the unit of the value you entered (g/dL, g/L, mmol/L Hb(Fe), mmol/L tetramer, mg/dL or mg/L).
Optionally enter the low and high limits printed on the same laboratory report, using the selected input unit.
All five unit equivalents appear below the input.
If both report limits are supplied, the tool compares the result with that user-provided interval without diagnosing a condition.
Optionally choose a WHO population group, elevation of residence and smoking status. The tool subtracts the WHO 2024 adjustments from the measured value (in g/L) and compares the result with that group's cutoffs for mild, moderate and severe anaemia.

Use cases

Convert lab results from SI units (g/L or mmol/L) to the US standard g/dL.
Interpret hemoglobin values from international medical reports.
Compare a result with the exact reference interval printed by the reporting laboratory.
Compare hemoglobin readings from different laboratory systems.
Prepare consistent units for discussion with a qualified clinician.
Use the quick chart to look up common mass and Hb(Fe) substance concentrations.

Frequently Asked Questions

Last updated: 2026-10-09 · Reviewed by Nham Vu