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.

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.

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

Countries using the Système International (SI) report hemoglobin in mmol/L because SI standardizes all concentrations in molar units. The US, UK, Canada, and Australia typically report in g/dL or g/L.

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)), mg/dL, and mg/L. Any range comparison uses only the low and high values you enter from your laboratory report.

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.

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.

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Summary

Enter a hemoglobin result to convert it among g/dL, g/L, mmol/L (Hb(Fe)), mg/dL, and mg/L. Any range comparison uses only the low and high values you enter from your laboratory report.

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, or mg/dL).
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.

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: 2026-09-19 · Reviewed by Nham Vu