What this calculator does
Blood glucose is reported in mmol/L across most of the world and in mg/dL in the United States, which makes reading advice from the other convention needlessly confusing. The two differ by a fixed factor of 18.0182.
That factor is not arbitrary: it is the molar mass of glucose, 180.182 grams per mole, divided by ten. A reading of 5.5 mmol/L converts to 99.1 mg/dL and 10 mmol/L to 180.2.
The formula
Multiply mmol/L by 18.0182 to get mg/dL, or divide by the same factor to go the other way. The factor comes from glucose having a molar mass of 180.182 g/mol.
| Term | Meaning |
|---|---|
| mmol/L | Millimoles per litre: a count of molecules, used in most countries. |
| mg/dL | Milligrams per decilitre: a mass measure, used in the United States. |
| 18.0182 | The conversion factor, being the molar mass of glucose divided by ten. |
The inputs explained
| Field | What to enter |
|---|---|
| Value | The reading to convert, in whichever unit you selected below. |
| Convert | Which direction to convert in. |
When to use it
Reading international guidance
Targets published in the other unit need converting before they mean anything.
Using a meter bought abroad
Devices are configured for their local convention.
Comparing lab results
Results from different countries arrive in different units.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
What do common readings convert to?
Three readings across the range.
| Reading (mmol/L) | Equivalent in mg/dL | Conversion factor |
|---|---|---|
| 1.5 mmol/L | 27.0 mg/dL | × 18.0182 |
| 5 mmol/L | 90.1 mg/dL | × 18.0182 |
| 10 mmol/L | 180.2 mg/dL | × 18.0182 |
Questions
Why do two units exist at all?
Because mmol/L counts molecules and mg/dL measures mass. The molar convention is the international standard and makes comparisons between substances easier; the mass convention predates it and remains entrenched in the United States.
Is there a quick mental conversion?
Multiplying by 18 is close enough for everyday use, since the true factor is 18.0182. Dividing by 18 works the other way. The error is well under one per cent.
Does the factor apply to other substances?
No. It is specific to glucose, because it comes from glucose's molar mass. Cholesterol, creatinine and everything else each have their own factor.
What are typical target ranges?
They depend on the individual, on whether they have diabetes and on what treatment they are using. Targets should come from the clinician managing that care rather than from a general figure.
For average glucose from an A1C result, see the estimated average glucose calculator. For cholesterol unit conversion, see the cholesterol units calculator.