Convert blood test results between conventional and SI units — the factor comes from the molar mass and never goes out of date.
Blood test results mean the same thing everywhere, but laboratories in different countries — and sometimes in the same country — print them in different units. A glucose of 100 mg/dL and a glucose of 5.55 mmol/L are the same concentration of the same molecule in the same blood: the number changed because the unit changed, not because the patient is different. The conventional system measures mass per volume (milligrams per decilitre), and the SI system measures substance per volume (millimoles per litre). Most of the world has moved to SI; the United States, Japan and parts of Latin America still print many results in conventional units. A Brazilian lab may report creatinine in mg/dL and a European one in µmol/L, and the patient searching for a reference range online finds articles in the other system.
The conversion factor between the two is not a convention that someone decided — it comes from the molar mass of the substance. Glucose has a molar mass of 180.16 grams per mole, so the factor is 10 ÷ 180.16 = 0.05551: multiply mg/dL by that and you get mmol/L. The same arithmetic, the same answer, in every laboratory on the planet and for as long as glucose remains glucose. That is why this page shows the molar mass next to the factor: it is the proof, not a footnote. A few tests use a different kind of factor — enzyme activities measured in international units convert to katals by a fixed SI definition, and the HbA1c uses the NGSP/IFCC master equation, which has a subtraction in it because it maps between two calibration systems, not two concentration units.
One thing this page does not do, deliberately and conspicuously: it does not say whether a result is normal. A reference interval depends on the analytical method, the equipment, the reagent lot, your age, your sex and often your recent meals. The interval printed on your own lab report is the one that applies, and reading it — deciding whether that number means something — is the doctor's job. Converting a unit is arithmetic; interpreting a result is medicine. This tool does the first and stops there. Everything runs in your browser: the value you type is never uploaded, stored or sent anywhere.
SI value = conventional value × factor. The factor for most analytes is 10 ÷ molar mass (mg/dL → mmol/L) or 10000 ÷ molar mass (mg/dL → µmol/L). Enzyme activities: 1 U/L = 0.01667 µkat/L (by SI definition). HbA1c: IFCC (mmol/mol) = (NGSP% − 2.15) × 10.929 (NGSP/IFCC master equation).
History. The conventional system (mg/dL, µg/dL) was established when clinical chemistry measured mass. The SI system (mmol/L, µmol/L) measures the number of molecules, which is what matters biologically. Most of the world adopted SI; the US and some other countries kept the conventional system, and many labs print both.
No. It comes from the molar mass of the substance, which is a physical constant. As long as glucose weighs 180.16 grams per mole, the factor is 0.05551. The molar mass is shown on screen so you can verify it.
No, and it will not. Whether a value is within range depends on the method, the equipment, your age, your sex and your history. The reference interval printed on your own report is the one that applies, and interpreting it is the doctor's job.
It is not a unit conversion but a mapping between two calibration systems: NGSP (%) and IFCC (mmol/mol). The master equation is IFCC = (NGSP − 2.15) × 10.929. The subtraction exists because the two methods measure slightly different fractions of the haemoglobin molecule.
No. The value you type and the converted result are calculated in JavaScript on your own device. Nothing is uploaded, stored or logged anywhere.
Because the two units are already the same concentration written differently. A nanogram per millilitre and a microgram per litre are mathematically identical, and so are milliequivalents per litre and millimoles per litre for monovalent ions like sodium and potassium. The factor is 1, and only the label changes.
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