Blood Sugar Converter: mg/dL to mmol/L and mmol/L to mg/dL
Blood glucose (blood sugar) is reported in two different units depending on where you are in the world. The United States and a handful of other countries use mg/dL (milligrams per deciliter), a mass-based unit. Most of the rest of the world — including the UK, Canada, and much of Europe — uses mmol/L (millimoles per liter), which measures the molar concentration of glucose instead of its weight.
Because the same blood sugar level looks like a completely different number depending on the unit, converting between mg/dL and mmol/L is something people with diabetes, caregivers, and healthcare providers run into often — whether you're reading a glucose meter from a different country, comparing lab results, or just trying to understand a number your doctor mentioned in a different unit.
You'll typically need to convert glucose units when:
- Traveling or relocating: Your glucose meter or local lab may report in a different unit than you're used to
- Reading international guidelines: Medical literature and diabetes associations from different countries often use different units
- Comparing lab reports: Older results or reports from a different healthcare system may use the unit you're not familiar with
- Understanding a doctor's explanation: Clinicians sometimes reference both units when discussing targets
The calculator above converts instantly between the two units. It is designed for glucose specifically; conversion factors for cholesterol, ketones, and other substances are different. For related health tools, explore our full range of medical calculators.
How to Use the Blood Glucose Converter
- Enter your glucose reading in either the mg/dL field or the mmol/L field.
- The matching value appears instantly in the other field. You can also press Convert or the Enter key.
- Use Copy to save the result or Print Chart for an offline conversion reference.
The Glucose Conversion Formula
Converting mg/dL to mmol/L:
mmol/L = mg/dL ÷ 18.0182
Converting mmol/L to mg/dL:
mg/dL = mmol/L × 18.0182
The calculator uses 18.0182. For quick mental math, this is commonly rounded to 18. Published medical conversion tables also express the reverse conversion as mg/dL × 0.0555.
Worked Example
Say your glucose meter shows 126 mg/dL and you want to know the equivalent in mmol/L:
- Take the mg/dL value: 126
- Divide by 18.0182: 126 ÷ 18.0182 ≈ 6.99
- Result: 6.99 mmol/L (usually displayed as 7.0)
Going the other way, if a lab report shows 5.5 mmol/L:
- Take the mmol/L value: 5.5
- Multiply by 18.0182: 5.5 × 18.0182 ≈ 99.1
- Result: 99.1 mg/dL (usually displayed as 99)
Blood Sugar Conversion Chart
Use this quick chart for common glucose readings. Values are rounded in the same practical way used by many glucose meters and published conversion tables.
| mg/dL | mmol/L | mg/dL | mmol/L |
|---|---|---|---|
| 40 | 2.2 | 220 | 12.2 |
| 50 | 2.8 | 240 | 13.3 |
| 60 | 3.3 | 250 | 13.9 |
| 70 | 3.9 | 260 | 14.4 |
| 80 | 4.4 | 280 | 15.5 |
| 90 | 5.0 | 300 | 16.7 |
| 100 | 5.6 | 320 | 17.8 |
| 110 | 6.1 | 340 | 18.9 |
| 120 | 6.7 | 360 | 20.0 |
| 126 | 7.0 | 380 | 21.1 |
| 130 | 7.2 | 400 | 22.2 |
| 140 | 7.8 | 420 | 23.3 |
| 150 | 8.3 | 440 | 24.4 |
| 160 | 8.9 | 450 | 25.0 |
| 180 | 10.0 | 460 | 25.5 |
| 200 | 11.1 | 500 | 27.8 |
Fasting and Glucose-Test Reference Ranges
The values below are laboratory diagnostic references for nonpregnant adults. They are not a label for every home-meter or continuous-glucose-monitor reading. Timing and test type matter.
| Test context | Category | mg/dL | mmol/L |
|---|---|---|---|
| Fasting plasma glucose | Normal | 99 or below | 5.5 or below |
| Prediabetes range | 100–125 | 5.6–6.9 | |
| Diabetes range | 126 or above | 7.0 or above | |
| 2-hour oral glucose tolerance test | Normal | 139 or below | 7.7 or below |
| Prediabetes range | 140–199 | 7.8–11.0 | |
| Diabetes range | 200 or above | 11.1 or above |
A diagnosis is made by a qualified healthcare professional using the appropriate test and, when required, repeat confirmation. Personal glucose targets may differ. For many people with diabetes, a reading below 70 mg/dL (3.9 mmol/L) is considered low, but individual thresholds can vary.
Why Do Countries Use Different Glucose Units?
mg/dL measures glucose by weight — how many milligrams of glucose are present in one deciliter of blood. It's the standard in the United States and a few other countries.
mmol/L measures glucose by molar concentration — the actual number of glucose molecules present in one liter of blood. This is the SI (International System of Units) standard, and it's what most countries, including the UK, Canada, Australia, and much of Europe, use on lab reports and glucose meters.
Neither unit is "more correct" than the other — they're just different ways of expressing the same underlying measurement, similar to how temperature can be expressed in Fahrenheit or Celsius.
mg/dL, mmol/L and mmol/mol: What Is the Difference?
These similar-looking units do not all describe the same measurement. Use the table below before converting a meter reading, laboratory result or HbA1c result.
| Unit | What it reports | Common use | Use this converter? |
|---|---|---|---|
| mg/dL | Mass concentration of glucose | Blood glucose meters and lab reports, especially in the US | Yes |
| mmol/L | Molar concentration of glucose | Blood glucose meters and lab reports in the UK, Canada, Australia and many other countries | Yes |
| mmol/mol | HbA1c in IFCC units | Longer-term blood sugar assessment over roughly 2–3 months | No — it requires an HbA1c conversion |
Can one blood glucose reading be converted to HbA1c? Not reliably. A single random or fasting blood sugar reading is a snapshot, while HbA1c reflects longer-term glucose exposure. An HbA1c-to-estimated average glucose calculation is a separate calculation and is not the same as converting mg/dL to mmol/L.
Common Mistakes When Reading Glucose Units
Mixing up the two units is one of the most common sources of confusion when people switch glucose meters, travel internationally, or read a foreign lab report. A reading of "5.5" could mean a healthy fasting glucose (5.5 mmol/L) or a dangerously low one if misread as 5.5 mg/dL. Always double-check which unit your device or report is using before interpreting a number — especially if the value looks unusually high or low for the context.
Reference Sources
| Source | Relevance |
|---|---|
| NIDDK: Diabetes Tests & Diagnosis | Fasting plasma glucose and oral glucose tolerance test diagnostic ranges |
| NCBI Bookshelf: Glucose Conversion Table | Published mg/dL-to-mmol/L conversion values and formulas |
| NIDDK: Low Blood Glucose | Context for the commonly used below-70 mg/dL low-glucose threshold |
Using This Tool: This calculator is meant to help you quickly translate a glucose number between units so you can read an international meter, report, or guideline — not to diagnose diabetes or change medication. For related tools, browse our medical calculators.
Frequently Asked Questions
Divide the glucose value in mg/dL by 18.0182. For example, 180 mg/dL is approximately 9.99 mmol/L, commonly displayed as 10.0 mmol/L.
Multiply the glucose value in mmol/L by 18.0182. For example, 7.0 mmol/L is approximately 126.1 mg/dL, commonly displayed as 126 mg/dL.
A blood glucose reading of 7.4 mmol/L is approximately 133.3 mg/dL (7.4 × 18.0182). This is a unit conversion only; interpretation depends on timing, test type and your personal care plan.
For a fasting plasma glucose laboratory test, NIDDK lists 99 mg/dL (about 5.5 mmol/L) or below in the normal diagnostic category. Home-meter targets and after-meal readings require different context.
Not reliably. One glucose reading is a snapshot, whereas HbA1c reflects average glucose exposure over roughly 2–3 months. HbA1c and estimated average glucose use a separate calculation.
mmol/L reports the concentration of glucose in blood. mmol/mol is an IFCC unit for HbA1c. Do not use the glucose factor of 18.0182 to convert mmol/mol.
No. The factor 18.0182 is specific to glucose. Cholesterol, ketones, creatinine and other substances require different conversion factors.
Yes, when the number represents glucose and is reported in mg/dL or mmol/L. The arithmetic is the same, but medical interpretation can differ by device, sample type, timing and personal care plan.
