Blood sugar converter: mg/dL to mmol/L (and back)
To convert blood sugar from mmol/L to mg/dL, multiply by 18 (18.016 exactly); to convert mg/dL to mmol/L, divide by 18. So 100 mg/dL is 5.6 mmol/L, and 7.0 mmol/L is 126 mg/dL.
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Blood sugar converter
The conversion formula
mmol/L = mg/dL ÷ 18.016
mg/dL = mmol/L × 18.016
One molecule of glucose weighs 180.16 g/mol, so 1 mmol of glucose per liter is 180.16 mg per liter, or 18.016 mg per deciliter. Most people round this to 18. We show mg/dL as whole numbers and mmol/L to one decimal, the way meters and lab reports print them.
mg/dL to mmol/L chart
| mg/dL | mmol/L | What it means |
|---|---|---|
| 50 | 2.8 | — |
| 60 | 3.3 | — |
| 70 | 3.9 | Below 70 mg/dL is low blood sugar (hypoglycemia) for most people with diabetes (NIDDK) |
| 80 | 4.4 | — |
| 90 | 5.0 | — |
| 100 | 5.6 | Fasting: 100–125 mg/dL is the prediabetes range (CDC) |
| 110 | 6.1 | — |
| 120 | 6.7 | — |
| 126 | 7.0 | Fasting: 126 mg/dL or above is the diabetes range (CDC) |
| 140 | 7.8 | 2-hour glucose tolerance test: 140–199 mg/dL is the prediabetes range (CDC) |
| 160 | 8.9 | — |
| 180 | 10.0 | — |
| 200 | 11.1 | 2-hour glucose tolerance test: 200 mg/dL or above is the diabetes range (CDC) |
| 250 | 13.9 | — |
| 300 | 16.7 | — |
| 400 | 22.2 | — |
mmol/L to mg/dL chart
| mmol/L | mg/dL |
|---|---|
| 3.0 | 54 |
| 3.5 | 63 |
| 4.0 | 72 |
| 4.5 | 81 |
| 5.0 | 90 |
| 5.5 | 99 |
| 6.0 | 108 |
| 6.5 | 117 |
| 7.0 | 126 |
| 7.5 | 135 |
| 8.0 | 144 |
| 9.0 | 162 |
| 10.0 | 180 |
| 11.0 | 198 |
| 12.0 | 216 |
| 15.0 | 270 |
| 20.0 | 360 |
What your blood sugar numbers mean
These are the CDC ranges for blood sugar tests, shown in both units. A single home reading isn't a diagnosis; if your numbers fall in these ranges, talk to your doctor about testing.
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting blood sugar | 99 mg/dL or below (5.5 mmol/L or below) | 100–125 mg/dL (5.6–6.9 mmol/L) | 126 mg/dL or above (7.0 mmol/L or above) |
| 2-hour glucose tolerance test | Below 140 mg/dL (below 7.8 mmol/L) | 140–199 mg/dL (7.8–11.0 mmol/L) | 200 mg/dL or above (11.1 mmol/L or above) |
Frequently asked questions
How do you convert mmol/L to mg/dL?
Multiply the mmol/L value by 18.016 (about 18), which comes from the molar mass of glucose, 180.16 g/mol. For example, 6.0 mmol/L × 18.016 = 108 mg/dL.
How do you convert mg/dL to mmol/L?
Divide the mg/dL value by 18.016 (about 18). For example, 140 mg/dL ÷ 18.016 = 7.8 mmol/L.
Why do some converters use 18 and others 18.016?
18 is 18.016 rounded. The difference is under 0.1%, so for any real blood sugar reading the two give results within 1 mg/dL of each other.
What is a normal fasting blood sugar in mmol/L?
According to the CDC, a fasting blood sugar of 99 mg/dL (5.5 mmol/L) or below is normal, 100–125 mg/dL (5.6–6.9 mmol/L) is prediabetes, and 126 mg/dL (7.0 mmol/L) or above is in the diabetes range.
What blood sugar level is too low?
For most people with diabetes, a reading below 70 mg/dL (3.9 mmol/L) counts as low blood sugar (hypoglycemia), according to the NIDDK. Your own target may differ, so check with your care team.
Can I convert A1C with this converter?
No. A1C is the percentage of hemoglobin that has glucose attached, not a glucose concentration. Use the A1C calculator to turn an A1C into an estimated average glucose in mg/dL or mmol/L.