Blood Sugar Calculator — Glucose Levels & ADA Classification
Convert your blood glucose reading between mg/dL and mmol/L, see how it compares to ADA 2024 normal and prediabetes thresholds, and get an estimated HbA1c if this is your average glucose level — for fasting, 2-hour post-meal, or random readings.
Measurement context
Unit
mmol/L
Normal — Within normal range per ADA 2024
- 1
Convert mmol/L to mg/dL
5.5 × 18.016 = 99.1 - 2
Add ADAG offset
99.1 + 46.7 = 145.8 - 3
Estimated HbA1c
(145.8) ÷ 28.7 = 5.1ADAG formula — most meaningful when this glucose represents your 3-month average.
How does this calculator work?
Multiply mmol/L by 18.016 to get mg/dL. Per ADA 2024: fasting glucose is normal below 100 mg/dL, prediabetes 100–125, diabetes ≥ 126. Estimated HbA1c from average glucose is (glucose + 46.7) / 28.7. A single reading is not enough to diagnose — always confirm with a clinician.
Formula
How this is calculated
Blood glucose is measured in milligrams per decilitre (mg/dL) in the US and many other countries, and in millimoles per litre (mmol/L) in the UK, Europe, Australia, and Canada. The conversion is exact: 1 mmol/L = 18.016 mg/dL. This calculator performs the conversion in either direction.
Classification follows American Diabetes Association (ADA) 2024 Standards of Care. For fasting plasma glucose (at least 8 hours without food): below 100 mg/dL (5.6 mmol/L) is normal, 100–125 mg/dL (5.6–6.9 mmol/L) is impaired fasting glucose (prediabetes), and ≥ 126 mg/dL (7.0 mmol/L) meets the threshold for diabetes. For 2-hour values during an oral glucose tolerance test (OGTT): below 140 mg/dL (7.8 mmol/L) is normal, 140–199 mg/dL (7.8–11.0 mmol/L) is impaired glucose tolerance (prediabetes), and ≥ 200 mg/dL (11.1 mmol/L) is in the diabetes range.
The estimated HbA1c uses the ADAG (A1c-Derived Average Glucose) regression published in the ADA-validated formula: HbA1c = (average glucose mg/dL + 46.7) / 28.7. This is most meaningful when the glucose value represents your typical average over 3 months, not a single reading. Diagnosis of diabetes requires confirmation on a separate day or by a second method (OGTT, HbA1c, or fasting glucose).
Frequently asked questions
For fasting (8+ hours): below 100 mg/dL (5.6 mmol/L). For 2-hour post-meal: below 140 mg/dL (7.8 mmol/L). For HbA1c: below 5.7%. These are ADA 2024 thresholds for adults; targets for people already diagnosed with diabetes may differ.
Both measure glucose concentration. mg/dL is milligrams of glucose per decilitre of blood; mmol/L is millimoles per litre. The conversion factor is 18.016 — multiply mmol/L by 18 to get approximately mg/dL, or divide mg/dL by 18 to get mmol/L.
A single fasting glucose ≥ 126 mg/dL or a 2-hour OGTT value ≥ 200 mg/dL should be confirmed on a second day, unless symptoms of hyperglycaemia are present alongside a random glucose ≥ 200 mg/dL. Diagnosis requires clinical confirmation — do not self-diagnose.
TG we-Calculate Editorial Team. (2026). Blood Sugar Calculator — Glucose Levels & ADA Classification [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/blood-sugar-calculator
TG we-Calculate Editorial Team. "Blood Sugar Calculator — Glucose Levels & ADA Classification." TG we-Calculate. 2026. https://we-calculate.com/calculator/blood-sugar-calculator.
TG we-Calculate Editorial Team, "Blood Sugar Calculator — Glucose Levels & ADA Classification," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/blood-sugar-calculator
@misc{wecalculate_blood_sugar_calculator, title = {Blood Sugar Calculator — Glucose Levels & ADA Classification}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/blood-sugar-calculator}}, year = {2026}, note = {TG we-Calculate} }
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