Blood Glucose Converter: mg/dL ↔ mmol/L
Meters in the US read mg/dL; most other countries use mmol/L. Convert either way here.
How do I convert mg/dL to mmol/L? Divide by 18. For example, 100 mg/dL ÷ 18 ≈ 5.6 mmol/L.
The conversion
mmol/L = mg/dL ÷ 18.016, and mg/dL = mmol/L × 18.016. The factor comes from the molecular weight of glucose.
Reference table
| mg/dL | mmol/L |
|---|---|
| 70 | 3.9 |
| 80 | 4.4 |
| 90 | 5.0 |
| 100 | 5.6 |
| 126 | 7.0 |
| 140 | 7.8 |
| 180 | 10.0 |
| 200 | 11.1 |
Diagnostic thresholds for diabetes are set by your healthcare provider and local guidelines; this converter is for unit conversion only.
Fasting glucose ranges
For reference, the American Diabetes Association uses these fasting plasma glucose ranges for adults:
| Category | mg/dL | mmol/L |
|---|---|---|
| Normal | below 100 | below 5.6 |
| Prediabetes | 100–125 | 5.6–6.9 |
| Diabetes (on repeat testing) | 126 or above | 7.0 or above |
A home meter reading is not a diagnosis, because meters can differ by 10–15% from a lab result.
Glucose on a keto diet
Two things often surprise people. First, fasting glucose sometimes rises slightly after months on keto even when post-meal readings are low and stable. This is often called "adaptive glucose sparing" and is generally thought to be harmless in healthy people. Second, morning readings can run higher than evening ones because of the dawn effect, a normal early-morning hormone rise. Compare readings taken at the same time of day.
If you take medication that lowers blood glucose, low readings matter more than high ones. Check with your clinician before cutting carbs. See keto for diabetics.
Ketone readings are already reported in mmol/L on nearly all meters, so they need no conversion — use the GKI calculator to combine them.
Frequently asked questions
How do I convert mg/dL to mmol/L?
Divide by 18. For example, 100 mg/dL ÷ 18 ≈ 5.6 mmol/L.
Are ketones measured in mg/dL?
Home blood ketone meters almost always report mmol/L.