Blood Sugar Converter
Free blood sugar converter. Convert glucose levels between mg/dL and mmol/L. See normal ranges for fasting, post-meal, and A1C with diabetes risk assessment.
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Last updated: January 2026
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Frequently Asked Questions
What is the difference between mg/dL and mmol/L?
mg/dL (milligrams per deciliter) is used primarily in the US, while mmol/L (millimoles per liter) is the international standard. To convert: mg/dL ÷ 18 = mmol/L. For example, 100 mg/dL equals 5.6 mmol/L. Both measure the same thing—glucose concentration in blood—just with different units.
What is a normal fasting blood sugar level?
Normal fasting blood sugar is below 100 mg/dL (5.6 mmol/L). Pre-diabetes range is 100-125 mg/dL (5.6-6.9 mmol/L). Diabetes is diagnosed at 126 mg/dL (7.0 mmol/L) or higher on two separate tests. Fasting means no food or drinks (except water) for at least 8 hours.
What should blood sugar be 2 hours after eating?
For non-diabetics, blood sugar should be below 140 mg/dL (7.8 mmol/L) two hours after eating. 140-199 mg/dL (7.8-11.0 mmol/L) indicates pre-diabetes. 200 mg/dL (11.1 mmol/L) or higher suggests diabetes. Post-meal spikes are normal but should return to baseline within 2-3 hours.
What blood sugar level is dangerously low?
Blood sugar below 70 mg/dL (3.9 mmol/L) is considered hypoglycemia (low blood sugar). Symptoms include shakiness, sweating, confusion, and hunger. Below 54 mg/dL (3.0 mmol/L) is severe and requires immediate treatment with fast-acting glucose. Below 40 mg/dL can cause seizures or loss of consciousness.
How does A1C relate to average blood sugar?
A1C measures average blood sugar over 2-3 months. An A1C of 5.7% equals roughly 117 mg/dL average. Each 1% increase in A1C represents about 28 mg/dL higher average blood sugar. Normal A1C is below 5.7%, pre-diabetes is 5.7-6.4%, and diabetes is 6.5% or higher.