Blood Sugar Converter
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: August 20, 2026Two Units, One International Divide
Blood glucose is reported in mg/dL in the United States and in mmol/L across most of Europe, Canada, Australia, and elsewhere — a split that has nothing to do with the underlying measurement and everything to do with regional lab reporting conventions. Anyone reading a meter, lab result, or medical study from outside their home unit system runs into this conversion sooner or later.
The Formula
mg/dL = mmol/L × 18.0182
The conversion factor comes from the molar mass of glucose (approximately 180.18 g/mol) combined with the unit scaling between deciliters and liters.
Reference Conversion Table
| mg/dL | mmol/L |
|---|---|
| 70 | 3.9 |
| 100 | 5.5 |
| 126 | 7.0 |
| 140 | 7.8 |
| 180 | 10.0 |
| 200 | 11.1 |
These are unit conversions only, not clinical thresholds — interpretation of any specific value should follow guidance from a healthcare provider or the lab that issued the result.
When This Conversion Comes Up
- Traveling or relocating internationally — a glucose meter purchased abroad may default to the other unit system entirely.
- Reading international research or guidelines — clinical studies published outside the US typically report glucose in mmol/L.
- Comparing devices or lab reports — converting between units is necessary when comparing readings from sources that use different defaults.
How to Use This Calculator
- Enter your blood sugar value.
- Select the unit you're converting from: mg/dL or mmol/L.
- Select Calculate to see the converted value.
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Principles of Glycemic Measurement: mg/dL vs. mmol/L
A blood sugar converter translates blood glucose readings between the two international measurement unit systems used in clinical laboratory medicine and point-of-care glucometer devices worldwide. In endocrinology and diabetes management, accurate unit conversion prevents dangerous dosing miscalculations when patients travel internationally or reference foreign medical literature.
The Fundamental Blood Glucose Conversion Formulas
To Convert mmol/L to mg/dL: Blood Glucose (mg/dL) = mmol/L × 18.0182
Quick Approximation Factor: Divide mg/dL by 18 (or multiply mmol/L by 18)
ADA Diagnostic Thresholds for Diabetes Mellitus
| Diagnostic Test | Normal Range | Prediabetes | Diabetes Mellitus |
|---|---|---|---|
| Fasting Plasma Glucose | < 100 mg/dL (< 5.6 mmol/L) | 100 to 125 mg/dL (5.6 to 6.9 mmol/L) | ≥ 126 mg/dL (≥ 7.0 mmol/L) |
| 2-Hour Oral Glucose Tolerance (OGTT) | < 140 mg/dL (< 7.8 mmol/L) | 140 to 199 mg/dL (7.8 to 11.0 mmol/L) | ≥ 200 mg/dL (≥ 11.1 mmol/L) |
| HbA1c (Glycated Hemoglobin) | < 5.7% | 5.7% to 6.4% | ≥ 6.5% |
Estimated Average Glucose (eAG) from HbA1c
Example: HbA1c 7.0% = eAG 154 mg/dL (8.6 mmol/L)
Hypoglycemia Severity Classification
- Level 1 Hypoglycemia: Glucose < 70 mg/dL (< 3.9 mmol/L) — alert value requiring carbohydrate intake.
- Level 2 Hypoglycemia: Glucose < 54 mg/dL (< 3.0 mmol/L) — clinically significant; requires rapid glucose treatment.
- Level 3 Hypoglycemia: Severe cognitive impairment requiring third-party assistance or glucagon injection.
Continuous Glucose Monitoring (CGM) and Time in Range
Modern diabetes management has evolved beyond isolated glucose readings to Continuous Glucose Monitoring (CGM) metrics:
Time Below Range (TBR): Target = < 4% below 70 mg/dL (< 3.9 mmol/L)
Time Above Range (TAR): Target = < 25% above 180 mg/dL (> 10.0 mmol/L)
Glucose Management Indicator (GMI): Replaces laboratory HbA1c with CGM-derived average
Diabetic Ketoacidosis (DKA) Emergency Thresholds
When blood glucose exceeds 250 mg/dL (13.9 mmol/L) with positive urinary or blood ketones:
Diabetic Ketoacidosis (DKA) constitutes a life-threatening metabolic emergency requiring immediate intravenous insulin infusion, aggressive normal saline fluid resuscitation, and continuous electrolyte (potassium, bicarbonate) repletion in an intensive care setting.
Gestational Diabetes Glucose Targets
- Fasting Glucose: < 95 mg/dL (< 5.3 mmol/L)
- 1-Hour Postprandial: < 140 mg/dL (< 7.8 mmol/L)
- 2-Hour Postprandial: < 120 mg/dL (< 6.7 mmol/L)
International Unit System Differences by Country
| Measurement Unit | Countries Using This System |
|---|---|
| mg/dL (Milligrams per Deciliter) | United States, Japan, India, France, Germany, Egypt, Israel, Colombia |
| mmol/L (Millimoles per Liter) | United Kingdom, Canada, Australia, China, New Zealand, Scandinavia, most of Africa |
Insulin Dosing Correction Factor
Type 1 diabetes patients calculate bolus insulin correction doses based on current blood glucose relative to target:
Common ISF Rule: 1800 / Total Daily Insulin Dose (for rapid-acting insulin in mg/dL)
For mmol/L: ISF = 100 / Total Daily Dose
Self-Monitoring Blood Glucose (SMBG) Frequency Guidelines
- Type 1 Diabetes / Insulin Pump: 4 to 10 fingerstick checks daily (or continuous CGM sensor).
- Type 2 on Basal Insulin: Fasting AM check daily; periodic postprandial checks.
- Type 2 on Oral Medications Only: Per physician recommendation; typically 1 to 2 times daily.
Random Blood Glucose vs. Fasting Glucose Interpretation
Clinical interpretation of blood glucose levels depends critically on the testing context:
- Fasting Plasma Glucose (FPG): Measured after 8+ hours of overnight fasting. Diagnostic for diabetes at ≥ 126 mg/dL (≥ 7.0 mmol/L) on two separate occasions.
- Random (Non-Fasting) Plasma Glucose: A single random reading ≥ 200 mg/dL (≥ 11.1 mmol/L) with classic hyperglycemia symptoms (polyuria, polydipsia, unexplained weight loss) is diagnostic for diabetes mellitus.
- Postprandial Glucose (2 Hours After Meal): Normal < 140 mg/dL (< 7.8 mmol/L); elevated postprandial glucose is the earliest detectable sign of impaired glucose tolerance.
Glucometer Accuracy and FDA Standards
FDA-cleared point-of-care glucometers must achieve accuracy within ± 15% of laboratory plasma glucose reference values for readings ≥ 100 mg/dL and within ± 15 mg/dL for readings < 100 mg/dL.
Hyperglycemic Hyperosmolar State (HHS)
Distinct from DKA, Hyperglycemic Hyperosmolar State (HHS) occurs predominantly in Type 2 diabetes patients:
- Blood Glucose: Typically > 600 mg/dL (> 33.3 mmol/L)
- Serum Osmolality: > 320 mOsm/kg
- Minimal Ketosis: Unlike DKA, HHS presents with severe dehydration and altered mental status but minimal acidosis.
HHS carries a mortality rate of 10% to 20%, significantly higher than DKA, primarily due to the extreme dehydration and thromboembolic complications occurring in elderly and debilitated patients.
Diabetes Prevention Through Early Screening
The American Diabetes Association recommends screening all adults beginning at age 35, or earlier in individuals with elevated risk factors including obesity (BMI ≥ 25 kg/m2), first-degree family history of diabetes, history of gestational diabetes, or membership in high-risk ethnic groups. Early identification of prediabetes through fasting glucose and HbA1c testing enables intensive lifestyle intervention programs that reduce progression to frank Type 2 diabetes mellitus by 58%.