Formula: mg/dL = mmol/L × 18
Blood Sugar Unit Conversion: mmol/L and mg/dL
Glucose readings are reported in different units around the world: most countries including China use mmol/L (millimoles per liter), while the United States and Japan use mg/dL (milligrams per deciliter). When reading international research or using an imported meter, you often need to convert between the two.
The two units are linearly related: mg/dL = mmol/L × 18, and mmol/L = mg/dL ÷ 18. For example, a fasting glucose of 5.6 mmol/L is about 101 mg/dL, and 7.8 mmol/L after a meal is about 140 mg/dL.
The tool below converts in both directions in real time, and can also translate your HbA1c into an estimated average glucose (eAG) to help you understand how the numbers on your lab report relate. All calculations run locally in your browser.
Common Blood Sugar Conversion Chart
Common glucose values side by side in mmol/L and mg/dL. Read it in both directions: the mg/dL column on the right also tells you the matching mmol/L value.
| mmol/L | mg/dL |
|---|---|
| 1.0 | 18 |
| 2.0 | 36 |
| 3.0 | 54 |
| 3.9 | 70 |
| 4.0 | 72 |
| 4.4 | 79 |
| 5.0 | 90 |
| 5.6 | 101 |
| 6.0 | 108 |
| 7.0 | 126 |
| 8.0 | 144 |
| 10.0 | 180 |
| 11.1 | 200 |
| 13.9 | 250 |
| 16.7 | 300 |
| 22.2 | 400 |
| 25.0 | 450 |
| 33.3 | 600 |
HbA1c to Estimated Average Glucose Chart
HbA1c reflects your average glucose over the past 2–3 months. The table below follows the ADAG study formulas adopted by the ADA; categories reference ADA cutoffs.
| HbA1c | eAG (mg/dL) | eAG (mmol/L) | Category |
|---|---|---|---|
| 5.0 % | 97 mg/dL | 5.4 mmol/L | Normal |
| 5.7 % | 117 mg/dL | 6.5 mmol/L | Prediabetes |
| 6.0 % | 126 mg/dL | 7.0 mmol/L | Prediabetes |
| 6.5 % | 140 mg/dL | 7.7 mmol/L | Diabetes range |
| 7.0 % | 154 mg/dL | 8.5 mmol/L | Diabetes range |
| 8.0 % | 183 mg/dL | 10.1 mmol/L | Diabetes range |
| 9.0 % | 212 mg/dL | 11.7 mmol/L | Diabetes range |
| 10.0 % | 240 mg/dL | 13.3 mmol/L | Diabetes range |
Conversion Formulas
Glucose units
mg/dL = mmol/L × 18; mmol/L = mg/dL ÷ 18. The factor 18 comes from the molar mass of glucose (≈180 g/mol) and the 1 L = 10 dL unit relationship.
HbA1c → estimated average glucose (eAG)
eAG (mg/dL) = 28.7 × HbA1c − 46.7; eAG (mmol/L) = 1.59 × HbA1c − 2.59. These formulas come from the ADAG study endorsed by the ADA and estimate an individual’s average level.
Decimal places
By convention mg/dL is shown as a whole number and mmol/L to one decimal place. Convert with the exact factor first, then round at the end.
Blood Sugar Conversion FAQ
Just remember the factor 18: multiply mmol/L by 18 to get mg/dL, and divide mg/dL by 18 to get mmol/L. For example, 6.0 mmol/L × 18 = 108 mg/dL; 180 mg/dL ÷ 18 = 10.0 mmol/L.
It is a matter of historical and metrological convention. mmol/L is the SI molar-concentration unit used in China and most of Europe; mg/dL is a mass-concentration unit still used in the United States and Japan. Both describe the same measurement and are interchangeable with the factor 18.
5.6 × 18 = 100.8, roughly 101 mg/dL. This is also where the ADA’s fasting upper-normal limit comes from: above 5.6 mmol/L (≈100 mg/dL) falls into the prediabetes range (5.6–6.9 mmol/L, or 100–125 mg/dL).
Using the ADAG formula: 28.7 × 7 − 46.7 ≈ 154 mg/dL, about 8.5 mmol/L. For many people diagnosed with diabetes, 7% is a common HbA1c target — always follow your doctor’s individualized goal.
First check that the unit setting on your device or app matches your report. Rounding differences are normal: mg/dL displays whole numbers and mmol/L one decimal, so rounding can cause ±1 discrepancies. Glucose meters also allow roughly ±15% measurement error.
Yes. CGM (continuous glucose monitoring), meters, and glucose data in Apple Health all use the same unit systems, and most devices let you switch units in settings. When reading English research, foreign reports, or talking to doctors abroad, converting manually with this tool is also handy.
This conversion tool is for informational purposes only and is not medical advice. The HbA1c-to-eAG relationship follows the ADAG study formulas adopted by the ADA and estimates a population average. Consult a healthcare professional with any concerns.