Blood Test Unit Converter

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 (within the normal fasting range).
• 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 (well above the protective threshold).
• Triglycerides: 100 mg/dL × 0.0113 = 1.13 mmol/L (within optimal).
• Calcium: 100 mg/dL is far above the reference range — calcium is normally 8.5–10.5 mg/dL.

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). Per the 2018 ACC/AHA cholesterol guideline, 2.59 mmol/L (100 mg/dL) is the threshold typically used as the upper bound of optimal LDL for primary prevention; very-high-risk patients are usually targeted below 1.8 mmol/L (70 mg/dL) and, for recurrent atherosclerotic events, below 1.4 mmol/L (55 mg/dL) per the 2019 ESC/EAS guideline. To convert any LDL value: mmol/L = mg/dL × 0.02586 and mg/dL = mmol/L × 38.67.

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)	Cardiovascular risk band (hs-CRP)
0.05	0.5	Low risk
0.1	1.0	Low risk
0.3	3.0	Average risk
0.5	5.0	High risk (or active inflammation)
1.0	10.0	Suggests active infection or inflammatory process

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.

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.