Blood Sugar Converter
Why Are There Two Different Units?
If you are a diabetic traveling from the United States to Europe (or vice versa), looking at a glucose meter can be terrifying. A "normal" reading in the US is 90, but in the UK, a reading of 90 would mean you are in a diabetic coma.
This is because the world uses two different standards to measure the concentration of glucose in the blood:
- mg/dL (Milligrams per Deciliter): Used in the USA, Japan, France, India, and Israel. It measures the weight of glucose.
- mmol/L (Millimoles per Liter): Used in Canada, UK, Australia, China, and most of Europe. It measures the molecular count of glucose.
The Magic Number: 18
The math to switch between them is actually quite simple. The conversion factor is **18** (specifically 18.0182).
• mg/dL ÷ 18 = mmol/L
• mmol/L × 18 = mg/dL
Example: A reading of 5.5 mmol/L x 18 = 99 mg/dL.
Understanding Glucose Ranges
Knowing your number is only half the battle. You need to know what it means. Doctors typically look at "Fasting Plasma Glucose" (before you eat) to diagnose metabolic health.
| Category | mg/dL (US) | mmol/L (Intl) |
|---|---|---|
| Hypoglycemia (Low) | Below 70 | Below 3.9 |
| Normal (Fasting) | 70 - 99 | 3.9 - 5.5 |
| Pre-Diabetes | 100 - 125 | 5.6 - 6.9 |
| Diabetes | 126 or higher | 7.0 or higher |
What is HbA1c?
While a finger-prick test gives you a snapshot of your sugar at *this exact moment*, doctors prefer the HbA1c test (Hemoglobin A1c).
This test measures the percentage of red blood cells that have sugar attached to them. Because red blood cells live for about 3 months, the A1c test gives an average of your blood sugar over the last 90 days.
Our calculator provides an "Estimated A1c" based on your input. For example, if your average daily reading is 126 mg/dL, your A1c is roughly 6.0%.
Fasting vs. Post-Prandial
Your blood sugar naturally spikes after eating. This is normal. It is called the "Post-Prandial" spike.
- Fasting: Should be under 100 mg/dL (5.6 mmol/L).
- 2 Hours After Meal: Should be under 140 mg/dL (7.8 mmol/L).
If your numbers stay high (above 140) for hours after eating, it may indicate insulin resistance.