What this calculator does
A blood sugar converter switches a glucose reading between the two units used around the world: mg/dL (milligrams per decilitre), the standard in the United States and a few other countries, and mmol/L (millimoles per litre), used in most of the rest of the world including Australia, the UK and Canada. The same reading looks like a very different number depending on which unit a meter or lab report uses.
The blood sugar conversion between the two is a fixed physical relationship based on the molecular weight of glucose, not something that changes over time, so it is safe to apply directly: divide mg/dL by 18.0182 to get mmol/L, or multiply mmol/L by 18.0182 to get mg/dL.
The formula
Enter a reading and choose which direction to convert. The calculator divides by 18.0182 to go from mg/dL to mmol/L, or multiplies by 18.0182 to go the other way, and shows the result in both units side by side.
| Term | Meaning |
|---|---|
| mg/dL | Milligrams of glucose per decilitre of blood, the unit used in the United States. |
| mmol/L | Millimoles of glucose per litre of blood, the unit used in most other countries. |
| 18.0182 | The molar mass of glucose in grams per mole, which is the fixed factor linking the two units. |
The inputs explained
| Field | What to enter |
|---|---|
| Reading | The blood sugar reading to convert, in whichever unit you select below. |
| Convert | Choose the unit your reading is currently in, and this converts it to the other one. |
When to use it
Reading an overseas glucose meter or app
A meter or app bought or set up in a different country may report in the unit you are not used to; converting it into the familiar unit makes the number easier to compare against your own history.
Comparing a lab report against home readings
A pathology report and a home glucose meter sometimes use different units, and converting one into the other lines them up for a direct comparison.
Understanding a number from an overseas source
Health information written for a different country will often quote glucose ranges in the other unit, and converting a reading makes it possible to see how it relates to what that source is describing.
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.
mg/dL converted to mmol/L across a range of readings
A spread of typical mg/dL readings and their mmol/L equivalents.
| Reading (mg/dL) | In mmol/L |
|---|---|
| 70 | 3.88 mmol/L |
| 90 | 4.99 mmol/L |
| 100 | 5.55 mmol/L |
| 126 | 6.99 mmol/L |
| 140 | 7.77 mmol/L |
| 200 | 11.10 mmol/L |
mmol/L converted to mg/dL across a range of readings
A spread of typical mmol/L readings and their mg/dL equivalents.
| Reading (mmol/L) | In mg/dL |
|---|---|
| 4 | 72.1 mg/dL |
| 5 | 90.1 mg/dL |
| 5.5 | 99.1 mg/dL |
| 7 | 126.1 mg/dL |
| 7.8 | 140.5 mg/dL |
| 11.1 | 200.0 mg/dL |
Questions
Is this a diagnostic tool?
No. This converts a reading between two units of measurement only; it does not interpret whether a reading is high, low or within a typical range. What a particular number means for you is a question for a healthcare provider, who can take your personal history into account.
Why do different countries use different units for blood sugar?
It comes down to differing conventions in clinical chemistry rather than anything about the readings themselves. mg/dL expresses concentration by mass, while mmol/L expresses it by the number of glucose molecules present, and both describe the same underlying reading.
Is 18.0182 always the right conversion factor?
Yes, for glucose specifically. This factor is the molar mass of glucose, so it applies consistently to blood sugar (glucose) readings. It would not apply to other blood test units, such as cholesterol, which use a different molecule with a different molar mass.
Why does the mg/dL figure come out as a whole-ish number and mmol/L does not?
It is simply a property of the arithmetic. A round number like 100 mg/dL happens to convert to 5.55 mmol/L, and a round mmol/L figure like 5.5 converts to a less round mg/dL figure, since the two scales are not aligned to give whole numbers in both directions at once.
For the microgram-to-milligram scale used elsewhere in medication dosing, see the microgram to milligram converter. For mixing a liquid medication by concentration, see the mg to mL converter.