Blood Sugar Converter

The Blood Sugar Converter instantly converts blood glucose readings between mg/dL (milligrams per deciliter, used in the US) and mmol/L (millimoles per liter, used in most other countries). It also categorizes your reading so you know whether it falls in the normal, prediabetic, or diabetic range. Whether you're managing diabetes, interpreting a lab report, or checking a foreign device, this tool eliminates conversion confusion.

How to Use This Calculator

1. Enter your blood glucose value in either mg/dL or mmol/L.
2. Select your measurement context — fasting, post-meal (1–2 hours after eating), or random.
3. Click Convert to see the equivalent value in the other unit plus your category.

What This Calculator Measures

This calculator converts blood glucose units and assigns a clinical category based on standard thresholds.

• mg/dL: Milligrams of glucose per deciliter of blood — standard US unit.
• mmol/L: Millimoles of glucose per liter of blood — international standard.
• Fasting glucose: Measured after 8+ hours without food.
• Postprandial glucose: Measured 1–2 hours after a meal.

Formula or Logic

The conversion factor is 18.0182 (the molecular weight of glucose divided by 10). mg/dL ÷ 18.0182 = mmol/L. mmol/L × 18.0182 = mg/dL. Categories: Normal fasting < 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) on two separate tests.

Example Calculations

Example 1: Fasting reading of 108 mg/dL. Converted: 108 ÷ 18.02 = 5.99 mmol/L → Prediabetes range.

Example 2: Post-meal reading of 7.8 mmol/L. Converted: 7.8 × 18.02 = 140.6 mg/dL → Normal post-meal level (below 140 mg/dL).

Understanding Your Results

Normal fasting glucose is below 100 mg/dL (5.6 mmol/L). Post-meal levels should ideally remain below 140 mg/dL (7.8 mmol/L) at the 2-hour mark. Consistently elevated readings warrant medical evaluation and lifestyle review.

Common Mistakes to Avoid

• Confusing fasting and random glucose thresholds — categories differ by timing.
• Not calibrating your home glucose meter regularly, leading to inaccurate readings.
• Using a single high reading to self-diagnose diabetes — a clinical diagnosis requires repeat testing.
• Ignoring post-meal spikes, which can indicate insulin resistance even when fasting levels appear normal.