Convert a blood glucose result between mg/dL and mmol/L without changing what was measured. Start with the number and unit shown on your meter, continuous glucose monitor or laboratory report. US readers commonly see mg/dL; readers elsewhere may see mmol/L. Always check the actual unit rather than assuming it from your location.
This is a numerical converter, not a diagnosis or an insulin-dose calculator. A converted result does not tell you whether a reading is safe for you.
Blood glucose unit converter
Enter the original value in either unit. The other field updates automatically.
mg/dL to mmol/L: formula and rounding
This calculator uses the factor 18.018 in both directions:
- mmol/L = mg/dL ÷ 18.018
- mg/dL = mmol/L × 18.018
The display rounds mmol/L to one decimal place and mg/dL to a whole number. For example, 100 mg/dL displays as 5.6 mmol/L, while 5.0 mmol/L displays as 90 mg/dL. Converting an already rounded result back can give a slightly different number. Keep the original reading and its unit when recording or sharing a result.
Glucose conversion examples
These are arithmetic examples, not target ranges, diagnostic cut-offs or treatment instructions.
| Original value | Converted display |
|---|---|
| 90 mg/dL | 5.0 mmol/L |
| 100 mg/dL | 5.6 mmol/L |
| 150 mg/dL | 8.3 mmol/L |
| 5.0 mmol/L | 90 mg/dL |
| 7.0 mmol/L | 126 mg/dL |
| 10.0 mmol/L | 180 mg/dL |
Conversion is different from interpretation
A unit conversion does not account for when you last ate, symptoms, pregnancy, medicines or your agreed glucose targets. Use your care team's monitoring and action plan, not this converter, to decide what to do about a reading.
NIDDK explains that home glucose meters cannot diagnose diabetes. Diagnosis uses appropriate healthcare testing and may require confirmation. A two-hour oral glucose tolerance test follows a specific glucose drink; it is not the same as an ordinary reading after a meal. See the American Diabetes Association's explanation of diagnostic tests.
When not to wait for a conversion
If you think you have low glucose, follow your agreed hypo plan promptly rather than waiting to convert the number. Loss of consciousness or a seizure is an emergency: call 911 in the US, or your local emergency number elsewhere. Do not give food or drink to someone who cannot swallow safely. NIDDK's low-glucose guidance explains emergency help; the NHS guidance also covers safe first aid.
Common questions
Can I use this to change my CGM's units?
No. The converter changes only the number displayed on this page, not your device, app, alarms or treatment settings. Check the unit printed alongside each reading and follow your device's instructions.
Why does a blank or invalid entry clear the result?
A result should belong to the current entry. Clearing it prevents an old conversion from being mistaken for a new reading. The input limits are technical limits of this tool, not healthy glucose ranges.
Is this an HbA1c converter?
No. This tool converts a glucose concentration. For the separate relationship between HbA1c and estimated average glucose, use our HbA1c calculator and explanation.