Gly LogBlood sugar unit conversion: mg/dL ↔ mmol/L
The US, Korea, and Japan mainly use mg/dL, while the UK, Canada, Australia, and many other countries use mmol/L. You may need to convert when reading guidance from another country or using an imported meter.
The formula
- mg/dL → mmol/L: divide by 18. Example: 126 ÷ 18 = 7.0
- mmol/L → mg/dL: multiply by 18. Example: 5.5 × 18 = 99
The exact factor is 18.016, but 18 is accurate enough for everyday logging.
Conversion chart for common values
| mg/dL | mmol/L | Where you'll see it |
|---|---|---|
| 54 | 3.0 | Clinically significant low |
| 70 | 3.9 | Low blood sugar threshold |
| 100 | 5.6 | Upper limit of normal fasting |
| 126 | 7.0 | Fasting diabetes threshold |
| 130 | 7.2 | Common upper pre-meal target |
| 140 | 7.8 | Normal 2-hour glucose tolerance test limit |
| 180 | 10.0 | Common upper after-meal target |
| 200 | 11.1 | 2-hour glucose tolerance test diabetes threshold |
| 250 | 13.9 | High blood sugar — take note |
If you switch units, write the unit at the top of your log. Without it, a "7" could be mmol/L or a typo.
This article is general health information and does not replace diagnosis or treatment. Targets and how often to check differ from person to person, so follow your care team first. If you have symptoms of low blood sugar or readings far outside your range, contact your care team right away.
Reference: American Diabetes Association (ADA) Standards of Care
Last updated 2026-10-26