Why are blood test units different between countries?

The United States primarily uses conventional units (e.g., mg/dL), while most other countries adopted the SI (Systeme International) system in the 1970s, which uses units like mmol/L. The difference is historical: the US medical system retained the older measurement conventions while the rest of the world standardized to SI units for scientific consistency.

How do I convert mg/dL to mmol/L?

The conversion factor depends on the specific biomarker because each has a different molecular weight. For glucose, multiply mg/dL by 0.0555 to get mmol/L. For cholesterol, multiply mg/dL by 0.0259. Our converter handles 50+ biomarkers automatically so you don't need to memorize the factors.

Do all blood tests use different units internationally?

No. Some blood tests use the same units worldwide. For example, HbA1c is reported as a percentage globally, and TSH is measured in mIU/L (or µIU/mL, which is equivalent) in both systems. However, most chemistry and hormone tests have different conventional and SI units.

What is the difference between conventional and SI units?

Conventional units typically express concentrations as mass per volume (e.g., mg/dL, ng/mL), while SI units express concentrations as moles per volume (e.g., mmol/L, nmol/L). SI units are based on the molecular weight of the substance, providing a more scientifically standardized measurement.

Can incorrect unit conversion affect my health decisions?

A unit mismatch can change a value by a large factor. Always verify the biomarker and unit printed on the original laboratory report. This calculator performs a mechanical conversion only and does not assess what a result means for an individual.

What is the soluble transferrin receptor (sTfR) and why is it on an anemia panel?

Soluble transferrin receptor (sTfR) is a circulating fragment of the cell-surface transferrin receptor. Its concentration rises when cells are iron-starved, so sTfR (and the sTfR/log-ferritin index) helps distinguish true iron-deficiency anemia from anemia of chronic disease, a distinction ferritin alone often cannot make because ferritin is an acute-phase reactant. sTfR is reported in mg/L; reference ranges vary by assay (commonly ~2.2–5.0 mg/L for adults).

Blood Test Unit Converter

Convert blood test results between conventional units (mg/dL, ng/dL) and SI units (mmol/L, nmol/L) for over 50 biomarkers. Select your biomarker, enter a value, and get an instant conversion.

Biomarker

Value

From

How to Convert Blood Test Units

Blood test results can be reported in different measurement units depending on the country, laboratory, or healthcare system. The two main systems are conventional units (commonly used in the United States) and SI units (Système International, used in most other countries). This can make it confusing to compare results from different labs or understand values from international medical literature.

Why Do Different Countries Use Different Units?

The United States primarily uses conventional units such as mg/dL (milligrams per deciliter) and ng/dL (nanograms per deciliter). Most of Europe, Australia, Canada, and the rest of the world use SI units such as mmol/L (millimoles per liter) and nmol/L (nanomoles per liter). The SI system was adopted internationally in the 1970s to standardize scientific measurement, but the US medical system largely retained the older conventional system.

This means a glucose reading of 100 mg/dL in the US is the same as 5.55 mmol/L in Europe. Both values are identical, just expressed differently.

Common Blood Test Unit Conversions

Biomarker	Conventional Unit	SI Unit	Multiply by
Glucose	mg/dL	mmol/L	0.0555
Total Cholesterol	mg/dL	mmol/L	0.0259
LDL Cholesterol	mg/dL	mmol/L	0.0259
HDL Cholesterol	mg/dL	mmol/L	0.0259
Triglycerides	mg/dL	mmol/L	0.0113
Creatinine	mg/dL	µmol/L	88.4
Uric Acid	mg/dL	µmol/L	59.48
Bilirubin (Total)	mg/dL	µmol/L	17.1
Testosterone	ng/dL	nmol/L	0.0347
Vitamin D (25-OH)	ng/mL	nmol/L	2.496
Vitamin B12	pg/mL	pmol/L	0.7378
Iron	µg/dL	µmol/L	0.1791
Cortisol	µg/dL	nmol/L	27.59
Hemoglobin	g/dL	g/L	10

How Unit Conversion Works

Each biomarker has a specific conversion factor based on its molecular weight. To convert from conventional units to SI units, you multiply by the conversion factor. To convert back, you divide by it. For example:

Glucose: 100 mg/dL × 0.0555 = 5.55 mmol/L
Total Cholesterol: 200 mg/dL × 0.0259 = 5.18 mmol/L
Creatinine: 1.0 mg/dL × 88.4 = 88.4 µmol/L
Testosterone: 500 ng/dL × 0.0347 = 17.35 nmol/L

Worked Examples for Common Queries

The questions below cover the conversions most readers ask about. Each one is biomarker-specific because molecular weights differ, so a single mg/dL value maps to different mmol/L values depending on what is being measured.

What is 100 mg/dL in mmol/L?

The answer depends on the biomarker:

Glucose: 100 mg/dL × 0.0555 = 5.55 mmol/L.
Total cholesterol: 100 mg/dL × 0.0259 = 2.59 mmol/L.
LDL cholesterol: 100 mg/dL × 0.0259 = 2.59 mmol/L.
HDL cholesterol: 100 mg/dL × 0.0259 = 2.59 mmol/L.
Triglycerides: 100 mg/dL × 0.0113 = 1.13 mmol/L.
Calcium: 100 mg/dL × 0.2495 = 24.95 mmol/L.

What is 100 mg/dL LDL in mmol/L?

An LDL cholesterol value of 100 mg/dL equals 2.59 mmol/L. The conversion factor for LDL (and for HDL, VLDL, and total cholesterol) is 0.02586, derived from the average molecular weight of cholesterol (386.65 g/mol). To convert any LDL value: mmol/L = mg/dL × 0.02586 and mg/dL = mmol/L × 38.67. This numerical conversion does not classify the result; use the reference interval on the original report and discuss personal targets with a qualified healthcare professional.

Does 1 mg/dL CRP equal mg/L? How do I convert?

1 mg/dL of CRP equals 10 mg/L. Unlike the mg/dL ↔ mmol/L conversions above, this is not a molar conversion: CRP in mg/dL and CRP in mg/L describe the same molecule at the same concentration, just expressed against different volume units (1 deciliter = 100 mL = 0.1 liter). The conversion factor is therefore exactly 10:

CRP (mg/L) = CRP (mg/dL) × 10
CRP (mg/dL) = CRP (mg/L) ÷ 10

Quick reference table:

CRP (mg/dL)	CRP (mg/L)	Conversion
0.05	0.5	× 10
0.1	1.0	× 10
0.3	3.0	× 10
0.5	5.0	× 10
1.0	10.0	× 10

Note that hs-CRP (high-sensitivity CRP) measures the same molecule with a more sensitive assay; the same 10× mg/dL ↔ mg/L factor applies. The other CRP unit you may see is nmol/L: CRP (nmol/L) = CRP (mg/L) × 9.524 (CRP molecular weight ~115 kDa, but reported as the pentameric form).

Soluble transferrin receptor (sTfR) on an anemia panel

The soluble transferrin receptor (sTfR) is a circulating fragment of the cell-surface transferrin receptor (TfR1). When cells are iron-starved, TfR1 expression rises and more receptor is shed into plasma, so sTfR concentration goes up in true iron-deficiency anemia. Combined with ferritin (sTfR/log-ferritin index, the "Thomas plot"), sTfR helps separate iron-deficiency anemia from anemia of chronic disease, which ferritin alone often cannot do because ferritin is an acute-phase reactant and rises in inflammation. A typical anemia panel that includes sTfR therefore looks like: CBC + reticulocyte count, ferritin, iron, TIBC/transferrin saturation, sTfR, and CRP (to gauge inflammation). Reference ranges depend on the assay; commonly ~2.2–5.0 mg/L in adults. Read more: Soluble Transferrin Receptor (sTfR) reference ranges & clinical use, Ferritin, Iron (serum), and the Iron Saturation Calculator.

Common Conversions: Dedicated Answer Pages

For the highest-volume conversion queries, we publish dedicated pages that break the answer down per biomarker (because the same mg/dL value gives a different mmol/L answer depending on whether you are converting glucose, cholesterol, triglycerides, calcium, magnesium, or BUN). Each page shows the math for all common biomarkers in one place:

100 mg/dL to mmol/L 150 mg/dL to mmol/L 200 mg/dL to mmol/L 250 mg/dL to mmol/L 500 mg/dL to mmol/L 1 mg/dL to mmol/L 5 mg/dL to mmol/L 10 mg/dL to mmol/L 50 mg/dL to mmol/L 55 mg/dL to mmol/L 70 mg/dL to mmol/L 231 mg/dL to mmol/L 5 mmol/L to mg/dL 7 mmol/L to mg/dL 10 mmol/L to mg/dL

Dedicated converters by substance

If you know which substance you are converting, the per-substance pages carry the cited conversion factor, published reference intervals, and pre-computed answers for the values people search most:

LDL cholesterol converter Total cholesterol converter HDL cholesterol converter Triglycerides converter Glucose converter Creatinine converter Uric acid converter CRP converter Bilirubin converter Hemoglobin converter Testosterone converter HbA1c converter nmol/L to mg/dL by substance

Popular biomarker-specific examples

These pages show the arithmetic for frequently searched value and biomarker combinations. They convert units only and do not classify a result.

Creatinine: 1.2 mg/dL to µmol/L Free T4: 1.2 ng/dL to pmol/L Bilirubin: 1 mg/dL to µmol/L Creatinine: 1 mg/dL to µmol/L Cortisol: 15 µg/dL to nmol/L Testosterone: 20 nmol/L to ng/dL Vitamin D: 30 ng/mL to nmol/L Testosterone: 300 ng/dL to nmol/L Uric acid: 380 µmol/L to mg/dL Uric acid: 6 mg/dL to µmol/L Vitamin D: 75 nmol/L to ng/mL Creatinine: 88 µmol/L to mg/dL

Or use the converter at the top of this page for any other value or unit pair.

Tips for Comparing Blood Test Results

Always check the units printed on your lab report before comparing values with reference ranges or past results.
When comparing results from different labs or countries, convert to the same unit system first.
Some biomarkers (like HbA1c or TSH) use the same units worldwide, so no conversion is needed.
If in doubt, ask your healthcare provider to clarify which units your results are in.

Educational use only: This tool performs mechanical unit conversions and provides general informational context. It does not diagnose, assess whether a result is healthy, recommend treatment, or replace a qualified medical professional. Conversion factors may vary slightly between laboratories; use the units and reference interval on your original report and discuss personal questions with your healthcare provider.

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Health3 helps you import, organize, convert, and chart lab results over time. It provides educational context and does not diagnose conditions or replace medical care.