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The Blood Sugar Unit Converter translates blood glucose readings between mg/dL (United States, used in clinical reports, glucose meters, and lab work) and mmol/L (United Kingdom, European Union, Australia, Canada — the SI standard). Conversion factor: divide mg/dL by 18.0182 to get mmol/L, or multiply mmol/L by 18.0182 to get mg/dL. The number 18.0182 reflects the molecular weight of glucose (180.16 g/mol) divided by 10. Clinical ranges are unit-specific. A fasting glucose of 100 mg/dL converts to 5.6 mmol/L — both represent the same biological state (top of normal fasting range, approaching prediabetes at 100+ mg/dL or 5.6+ mmol/L per ADA criteria). Postprandial (after-meal) ranges differ from fasting: normal under 140 mg/dL (7.8 mmol/L) two hours after eating; diabetes diagnosed at sustained 200+ mg/dL (11.1 mmol/L). The calculator outputs not just the converted number but a clinical category (Hypoglycemia, Normal, Prediabetes, Diabetes) based on whether you specify fasting or postprandial context. Hypoglycemia is defined as below 70 mg/dL (3.9 mmol/L) regardless of timing — a medical emergency requiring immediate sugar intake. These thresholds follow American Diabetes Association (ADA), American Association of Clinical Endocrinologists (AACE), and WHO criteria. Who needs this converter: International diabetics travelling between regions, patients reviewing lab results from foreign systems, families with multinational members comparing readings, healthcare professionals working across reference standards, researchers reading international literature, and continuous glucose monitor (CGM) users whose devices may default to a non-local unit. Always consult your healthcare provider for treatment decisions — this calculator provides only the mechanical unit conversion plus reference ranges.
- 1Step 1 — Enter your blood glucose reading from your meter, CGM, or lab report
- 2Step 2 — Select the source unit (mg/dL for US devices, mmol/L for UK/EU/AU/CA devices)
- 3Step 3 — Select the measurement context (fasting after 8+ hours, or postprandial 1–2 hours after eating)
- 4Step 4 — Calculator divides mg/dL by 18.0182 or multiplies mmol/L by 18.0182 to convert
- 5Step 5 — Output displays both units simultaneously for easy reference
- 6Step 6 — Clinical category appears (Hypoglycemia / Normal / Prediabetes / Diabetes range) based on ADA criteria
- 7Step 7 — Use the converted value to communicate with international healthcare providers or compare against locally-published ranges
100 mg/dL is the upper boundary of normal fasting glucose per ADA
100 ÷ 18.0182 = 5.55 mmol/L. Normal fasting range is 70–99 mg/dL (3.9–5.5 mmol/L).
8.0 × 18.0182 = 144.1 mg/dL. Normal 2-hour postprandial is under 140 mg/dL.
180 ÷ 18.0182 = 9.99 mmol/L. Fasting glucose 126+ mg/dL (7.0 mmol/L) qualifies for diabetes diagnosis per ADA.
Below 70 mg/dL (3.9 mmol/L) is hypoglycemia; below 54 mg/dL (3.0 mmol/L) is severe hypoglycemia requiring urgent treatment.
International travel with diabetes
Reviewing lab reports from foreign healthcare systems
Multi-country family glucose monitoring
Reading international diabetes research literature
CGM data sharing with overseas providers
Why are there two different units globally?
The US adopted mg/dL (mass concentration) historically while most of the world uses mmol/L (molar concentration, SI standard). Both are accurate; mmol/L is scientifically preferred because it represents actual moles of glucose. Switching the US would require relabeling all medical devices, lab reports, and patient education — a multi-decade transition that hasn't begun.
Are the diagnostic thresholds the same in both units?
Yes — the same biological state has equivalent thresholds in both units. ADA fasting normal: <100 mg/dL = <5.6 mmol/L. Prediabetes: 100–125 mg/dL = 5.6–6.9 mmol/L. Diabetes: 126+ mg/dL = 7.0+ mmol/L. The numbers look different but represent identical physiology.
How does HbA1c relate to these values?
HbA1c (glycated hemoglobin) reflects average blood glucose over 2–3 months. Estimated Average Glucose (eAG) formula: eAG mg/dL = (28.7 × A1c) − 46.7. So an A1c of 7% ≈ 154 mg/dL (8.5 mmol/L) average. A1c is reported as a percentage and doesn't have a mmol/L equivalent.
Can my CGM display in both units?
Yes — most CGMs (Dexcom, Libre, Medtronic) allow unit selection in app settings. If you travel internationally or share data with providers in different regions, you may need to switch back and forth. Some devices remember your preference per profile.
What if my reading varies a lot day to day?
Normal fluctuation is expected — glucose responds to food, stress, sleep, exercise, illness, and time of day. The diagnostic categories require confirmation over multiple readings or correlation with HbA1c. Track trends over weeks, not single readings.
Pro Tip
Always note whether a reading was fasting (8+ hours no food) or post-meal (1–2 hours after eating) — the same number means different things depending on context. Time-stamping every reading dramatically improves the value of your glucose log when reviewing patterns with your endocrinologist.
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