mg/dL to mmol/L Blood Sugar Converter
Convert blood glucose readings from mg/dL (used in the United States) to mmol/L (used in the UK, Canada, Europe, and Australia). Divide mg/dL by 18.018 to get mmol/L.
Blood Sugar Reference Ranges: mg/dL and mmol/L
The table below shows clinically important blood glucose thresholds in both mg/dL and mmol/L, based on ADA and WHO guidelines. These are the diagnostic criteria and treatment targets used by healthcare providers in the US (mg/dL) and internationally (mmol/L).
| Status | mg/dL | mmol/L |
|---|---|---|
| Normal fasting | 70 – 99 | 3.9 – 5.5 |
| Prediabetes fasting | 100 – 125 | 5.6 – 6.9 |
| Diabetes (fasting diagnosis) | ≥ 126 | ≥ 7.0 |
| Normal post-meal (2h) | < 140 | < 7.8 |
| Prediabetes post-meal | 140 – 199 | 7.8 – 11.0 |
| Diabetes (random + symptoms) | ≥ 200 | ≥ 11.1 |
| Hypoglycemia | < 70 | < 3.9 |
| Severe hypoglycemia | < 54 | < 3.0 |
| ADA target (fasting, diabetes) | 80 – 130 | 4.4 – 7.2 |
| ADA target (post-meal, diabetes) | < 180 | < 10.0 |
Worked Examples: mg/dL to mmol/L
Each example shows a clinically significant blood glucose value and its mmol/L equivalent. Formula: mmol/L = mg/dL ÷ 18.018.
mg/dL vs mmol/L: The Global Divide
The United States is one of the few countries that measures blood glucose in mg/dL. The rest of the world — including the UK, Canada, Australia, New Zealand, most of Europe, and most of Asia — uses mmol/L, which is the SI (International System of Units) standard for substance concentration in body fluids.
This creates frequent confusion for people who travel internationally, see foreign-trained doctors, or read medical research from other countries. A patient who has been managing their diabetes with a target of "below 180 mg/dL" post-meal needs to know that this is 10.0 mmol/L when speaking with a UK diabetes nurse. Similarly, a Canadian prescription that references a target of 7 mmol/L for HbA1c equivalent fasting glucose means 126 mg/dL.
Modern continuous glucose monitors (CGMs) and some newer glucometers can display in either unit. If you switch countries or switch devices, always verify which unit your device is using before interpreting results or adjusting insulin doses.
Common Blood Sugar Readings and Their Clinical Meaning
Fasting glucose (taken after 8+ hours without food) is the primary screening test for diabetes. Normal is below 100 mg/dL (5.6 mmol/L). Values of 100–125 mg/dL (5.6–6.9 mmol/L) indicate prediabetes — a condition where blood sugar is elevated but not yet at diabetic levels. A fasting glucose of 126 mg/dL (7.0 mmol/L) or higher on two separate tests meets the ADA diagnostic criteria for diabetes.
Post-meal glucose (2 hours after eating) is also used for diagnosis and monitoring. Normal is below 140 mg/dL (7.8 mmol/L). Values of 140–199 mg/dL (7.8–11.0 mmol/L) indicate prediabetes. Values of 200 mg/dL (11.1 mmol/L) or higher during an oral glucose tolerance test meet the diabetes diagnostic threshold.
Hypoglycemia (low blood sugar) is defined as blood glucose below 70 mg/dL (3.9 mmol/L) in people with diabetes. Severe hypoglycemia — below 54 mg/dL (3.0 mmol/L) — is a medical emergency. Symptoms include shakiness, sweating, confusion, rapid heartbeat, and in severe cases, loss of consciousness. Treatment involves fast-acting carbohydrates (glucose tablets, juice) followed by a meal or snack.
Frequently Asked Questions
How do I convert mg/dL to mmol/L?
Divide the mg/dL value by 18.018 to get mmol/L. For example, 126 mg/dL ÷ 18.018 = 6.99 mmol/L (7.0 mmol/L, the diabetes diagnostic threshold). For quick mental math, dividing by 18 gives an answer within 0.1% of the exact value.
What is 100 mg/dL in mmol/L?
100 mg/dL ÷ 18.018 = 5.55 mmol/L, typically rounded to 5.6 mmol/L. A fasting blood glucose of 100 mg/dL (5.6 mmol/L) is at the upper end of the normal fasting range and the lower boundary of the prediabetes range according to ADA guidelines.
What is 200 mg/dL in mmol/L?
200 mg/dL ÷ 18.018 = 11.1 mmol/L. A random (non-fasting) blood glucose of 200 mg/dL (11.1 mmol/L) or higher, combined with symptoms of diabetes such as frequent urination, excessive thirst, and unexplained weight loss, meets the ADA diagnostic criteria for diabetes.
What is a normal blood sugar in mg/dL and mmol/L?
A normal fasting blood glucose is 70–99 mg/dL (3.9–5.5 mmol/L). After a meal, normal levels remain below 140 mg/dL (7.8 mmol/L) at the two-hour mark. These are ADA and WHO reference standards for adults without diabetes.
What is 126 mg/dL in mmol/L?
126 mg/dL ÷ 18.018 = 6.99 mmol/L, rounded to 7.0 mmol/L. This is the fasting blood glucose diagnostic threshold for diabetes: a result of 126 mg/dL (7.0 mmol/L) on two separate occasions meets the ADA criteria for a diabetes diagnosis.
Why is the conversion factor 18.018?
The factor 18.018 is derived from the molecular weight of glucose (C₆H₁₂O₆), which is approximately 180.18 grams per mole. To convert from a molar concentration (mmol/L) to a mass concentration (mg/dL), you multiply by the molecular weight and adjust for the volume unit difference (1 liter = 10 deciliters): 180.18 ÷ 10 = 18.018. Dividing mg/dL by 18.018 reverses this calculation.
What blood sugar level is considered high in mg/dL?
Hyperglycemia (high blood sugar) in people with diabetes is generally defined as fasting glucose above 130 mg/dL (7.2 mmol/L) or post-meal glucose above 180 mg/dL (10.0 mmol/L). For people without diabetes, sustained levels above 140 mg/dL (7.8 mmol/L) are abnormal. Levels above 240 mg/dL (13.3 mmol/L) are severely elevated and may require urgent medical attention.
What is 70 mg/dL in mmol/L?
70 mg/dL ÷ 18.018 = 3.89 mmol/L, rounded to 3.9 mmol/L. This is the standard hypoglycemia threshold for people with diabetes — a blood glucose below 70 mg/dL (3.9 mmol/L) indicates low blood sugar that requires immediate treatment with fast-acting carbohydrates.
My US glucometer shows mg/dL but I need to report to a UK doctor in mmol/L — how do I convert?
Divide your mg/dL reading by 18.018 (or approximately 18 for quick mental math). For example, if your meter shows 108 mg/dL, that is 108 ÷ 18.018 = 5.99 mmol/L, or about 6.0 mmol/L. Many modern glucometers can also be switched between units in the settings menu.
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