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Blood Sugar Converter

Convert glucose mg/dL ↔ mmol/L and HbA1c ↔ average glucose, with normal ranges

mg/dL
Used only to describe the result against the reference ranges.
100 mg/dL is
5.6mmol/L
As a fasting reading
Borderline
Exact
5.55mmol/L
100–109 mg/dL is prediabetes by ADA criteria; ICMR counts prediabetes from 110 mg/dL.
mmol/L × 18.016 = mg/dL (many labs and apps round this to 18, which changes the answer by less than 0.1%). Home glucometers in India usually show mg/dL; the UK, Canada and Australia use mmol/L.
TestNormalPrediabetesDiabetes
Fasting plasma glucose< 110 mg/dL (ADA: < 100)110–125 mg/dL (ADA: 100–125)≥ 126 mg/dL (7.0 mmol/L)
2 h after 75 g glucose (OGTT)< 140 mg/dL140–199 mg/dL≥ 200 mg/dL (11.1 mmol/L)
HbA1c< 5.7%5.7–6.4%≥ 6.5%
Random plasma glucoseNot usedNot used≥ 200 mg/dL with symptoms

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For general information only, not medical advice. Talk to a doctor or a qualified professional about your health. Terms of use

How to Use

  1. Under Convert, choose what you have: mg/dL → mmol/L, mmol/L → mg/dL, HbA1c → average glucose, or average glucose → HbA1c.
  2. Type the number from your glucometer, lab report or glucose monitor.
  3. For glucose readings, pick When was it measured?: fasting, 2 hours after 75 g glucose (OGTT) or random. That way the result is compared with the right reference range.
  4. The converted value and its category update instantly. The reference ranges table below the result shows the ICMR and ADA cut-offs for every test.

mg/dL, mmol/L and HbA1c in one place

Labs and glucometers in India almost always report blood glucose in milligrams per decilitre (mg/dL). Many international guidelines, diabetes apps and relatives abroad use millimoles per litre (mmol/L), and HbA1c is a percentage that reflects your average over two to three months. This converter switches between all three and tells you where a value falls against the Indian (ICMR) and American Diabetes Association (ADA) reference ranges. It is general information to help you read a report, not a diagnosis.

The formulas

mmol/L = mg/dL ÷ 18.016  ·  mg/dL = mmol/L × 18.016
Estimated average glucose (mg/dL) = 28.7 × HbA1c − 46.7
HbA1c (%) = (average glucose in mg/dL + 46.7) ÷ 28.7

The factor 18.016 comes from the molar mass of glucose, 180.16 g/mol: one millimole per litre is 180.16 mg per litre, or 18.016 mg per decilitre. Many people round it to 18, which changes results only in the first decimal place. The HbA1c formula is from the international ADAG study (Nathan and colleagues, Diabetes Care, 2008), which the ADA uses for its “estimated average glucose” (eAG).

Worked examples

  • A fasting reading of 126 mg/dL ÷ 18.016 = 7.0 mmol/L, the diabetes threshold in both units.
  • A UK report showing 5.5 mmol/L × 18.016 = 99 mg/dL.
  • HbA1c 7%: 28.7 × 7 − 46.7 = 154 mg/dL (8.6 mmol/L) average glucose.

Reference ranges

TestNormalPrediabetesDiabetes
Fasting plasma glucose< 110 mg/dL (ADA: < 100)110–125 (ADA: 100–125)≥ 126 mg/dL
2 hours after 75 g glucose (OGTT)< 140 mg/dL140–199≥ 200 mg/dL
HbA1c< 5.7%5.7–6.4%≥ 6.5%
Random plasma glucoseNot usedNot used≥ 200 mg/dL with symptoms

Sources: ICMR Guidelines for Management of Type 2 Diabetes 2018, Table 3.1; American Diabetes Association Standards of Care. ICMR advises an OGTT when random glucose is 140–199 mg/dL, and any single positive test should be confirmed with another test. Readings below 70 mg/dL are low (hypoglycaemia) whatever the test.

The only difference between the two systems is the start of fasting prediabetes: ICMR uses 110 mg/dL (the WHO cut-off), while the ADA uses 100 mg/dL. The converter shows 100–109 mg/dL as “borderline” so you can see both views.

HbA1c and average glucose

HbA1cAverage glucose (mg/dL)Average glucose (mmol/L)
5%975.4
5.7%1176.5
6%1267.0
6.5%1407.8
7%1548.6
8%18310.2
9%21211.7
10%24013.3
12%29816.5

Things to keep in mind

  • Diagnosis is based on lab plasma glucose. Home glucometers are meant for monitoring and can differ from a lab result.
  • HbA1c can mislead in anaemia (common in India), after blood loss or transfusion, in pregnancy, in kidney disease and with some haemoglobin variants such as thalassaemia trait. Your doctor may then rely on glucose tests instead.
  • The average glucose from a continuous glucose monitor is often reported as GMI (glucose management indicator); it is similar to, but not the same as, a lab HbA1c.
  • Glucose targets for people already on treatment are set individually by the doctor, especially for older adults and in pregnancy.

Frequently Asked Questions

Multiply by 18 (more precisely 18.016). For example, 7 mmol/L × 18.016 = 126 mg/dL. To go the other way, divide mg/dL by 18.016: 180 mg/dL is 10.0 mmol/L.

By the ICMR 2018 guidelines, fasting plasma glucose below 110 mg/dL is normal, 110–125 mg/dL is impaired fasting glucose (prediabetes) and 126 mg/dL or more is in the diabetes range. The ADA uses a lower prediabetes start of 100 mg/dL. A single high result should be confirmed with a repeat test.

Using the ADAG formula (28.7 × HbA1c − 46.7), an HbA1c of 7% corresponds to an estimated average glucose of about 154 mg/dL, or 8.6 mmol/L, over the previous two to three months.

An HbA1c of 6.5% or higher is in the diabetes range according to both ICMR and the ADA. 5.7–6.4% is prediabetes and below 5.7% is normal. Conditions such as anaemia or haemoglobin variants can make HbA1c inaccurate, so doctors confirm with other tests.

Not exactly. The diagnostic cut-offs of 140 and 200 mg/dL are for a standard oral glucose tolerance test, 2 hours after drinking 75 g of glucose. A 2-hour post-meal (PP) test after a normal meal is useful for monitoring, but the load varies with what you ate, so discuss PP results with your doctor.

Home meters measure capillary blood from a finger prick and are allowed some error, while labs measure plasma from a vein. Timing, hand washing, strip storage and meter calibration also matter. Use lab results for diagnosis and the meter for day-to-day tracking.