Blood Sugar Conversion Calculator: mmol/L to mg/dL (+ Chart)

Whether you're traveling abroad, reading international diabetes research, or comparing your CGM results, having a reliable blood sugar conversion calculator is essential for understanding readings in both mmol/L and mg/dL. Different countries use different measurement systems, and knowing how to convert between mmol/L and mg/dL ensures you can accurately interpret your glucose readings anywhere in the world.

Want to track patterns beyond single readings? Learn about Time-in-Range metrics. New to glucose monitoring? See our guide for newly diagnosed individuals.

Understanding Blood Sugar Units: mg/dL vs mmol/L

Blood glucose can be measured in two primary units: mg/dL (milligrams per deciliter) and mmol/L (millimoles per liter). Both measure the concentration of glucose in your blood, but they use different systems:

• mg/dL: Used primarily in the United States, measures the mass of glucose per volume of blood
• mmol/L: Used internationally as part of the SI (International System of Units), measures the molecular concentration

Neither unit is inherently "better." They're simply different ways of expressing the same information. However, knowing both is crucial for understanding international guidelines, research papers, and medical equipment from different countries.

The Conversion Formula: Simple Math

The conversion between these units follows a consistent mathematical relationship:

The number 18.018 comes from the molecular weight of glucose and the conversion between different volume measurements. While you can do this math manually, our calculator above makes it instant and error-free.

Quick Reference Conversion Chart

Here's a comprehensive conversion table for common blood sugar values you'll encounter:

Target Blood Sugar Ranges in Both Units

Understanding target ranges in both measurement systems helps you interpret your results regardless of which unit your device uses:

For People Without Diabetes:

• Fasting (8+ hours no food): 70-100 mg/dL (3.9-5.6 mmol/L)
• Before meals: 70-100 mg/dL (3.9-5.6 mmol/L)
• 1-2 hours after eating: Below 140 mg/dL (7.8 mmol/L)
• Bedtime: 100-120 mg/dL (5.6-6.7 mmol/L)

For People With Diabetes (General Guidelines):

• Fasting/Before meals: 80-130 mg/dL (4.4-7.2 mmol/L)
• 1-2 hours after eating: Below 180 mg/dL (10.0 mmol/L)
• Bedtime: 90-150 mg/dL (5.0-8.3 mmol/L)
• A1C goal: Below 7% (53 mmol/mol) for most adults

Note: Your personal targets may differ based on your age, diabetes type, medications, and overall health. Always follow your healthcare provider's specific recommendations.

Why Different Countries Use Different Units

The split between mg/dL and mmol/L is largely geographical and historical:

United States: The US medical system has traditionally used conventional units (like mg/dL, inches, pounds) rather than metric/SI units. Most American glucose meters, CGMs, and medical literature use mg/dL.

Rest of the World: Most other countries adopted the International System of Units (SI), which includes mmol/L for blood glucose. This includes Canada, UK, Europe, Australia, and most of Asia.

Medical Research: International scientific journals increasingly use mmol/L, though many still provide both units for accessibility.

This divergence can create confusion when traveling, purchasing medical devices internationally, or reading research papers. That's why having a reliable conversion tool is essential.

Common Scenarios When You Need Conversion

Here are real-world situations where blood sugar unit conversion becomes necessary:

1. International Travel

If you travel from the US to Europe with your glucose meter displaying mg/dL, but local medical professionals ask for mmol/L readings, you'll need to convert on the fly. Some meters allow unit switching in settings, but knowing the conversion helps verify accuracy.

2. Purchasing Medical Devices Abroad

CGM sensors, glucose meters, and test strips bought internationally may default to mmol/L. Understanding conversion ensures you interpret results correctly.

3. Reading Research Studies

International diabetes research often uses mmol/L. If you're accustomed to mg/dL, converting helps you understand study results and whether they apply to your situation.

4. Telemedicine and International Consultations

With increasing access to international healthcare providers via telemedicine, you might need to communicate glucose values in units different from your usual system.

5. Comparing CGM Data

Some CGM apps allow unit selection. If you switch devices or share data with someone using different units, conversion prevents misinterpretation.

How to Change Units on Your Glucose Meter

Most modern glucose meters and CGMs allow you to switch between mg/dL and mmol/L in the device settings:

• Dexcom CGM: Settings → Units → Select mg/dL or mmol/L
• FreeStyle Libre: Settings → Preferences → Glucose Units
• OneTouch meters: Setup menu → Unit selection
• Contour Next: Settings → Units → Choose preferred unit

Important: After changing units, double-check your target ranges and alarm thresholds. A high alarm set for 180 mg/dL should be changed to 10.0 mmol/L, not kept at 180!

Tips for Avoiding Conversion Mistakes

Unit conversion errors can have serious consequences. Here's how to avoid them:

1. Always Label Your Units: When writing down glucose values, always include the unit (mg/dL or mmol/L) to avoid confusion later.
2. Double-Check Decimal Places: mmol/L values use decimals (e.g., 5.6), while mg/dL uses whole numbers (e.g., 100). This visual difference can help catch errors.
3. Use a Calculator: Manual math introduces error risk. Use our calculator above or a verified app for conversions.
4. Verify with Multiple Sources: If a converted value seems wrong, check with another calculator or reference chart.
5. Know Your Personal Ranges: Memorize your target ranges in both units. This helps you spot errors immediately.
6. Communicate Clearly with Healthcare Providers: When sharing glucose data, explicitly state which unit you're using to prevent misunderstandings.

Beyond Single Readings: Understanding Glucose Patterns

While knowing how to convert individual blood sugar readings is important, managing diabetes effectively requires understanding patterns over time. This is where metrics like Time-in-Range (TIR) and continuous glucose monitoring become invaluable.

Time-in-Range (TIR) measures the percentage of time your blood sugar stays within your target range (typically 70-180 mg/dL or 3.9-10.0 mmol/L). Research shows that higher TIR correlates with better long-term outcomes and reduced complication risk.

Apps like Glukee help you track not just individual readings but also:

• Glucose patterns throughout the day
• How meals affect your blood sugar
• Time spent in target range
• Trends over weeks and months
• Correlations between activities, foods, and glucose levels

Glukee lets you log in either mg/dL or mmol/L and keeps your patterns consistent no matter which unit you use.

Whether your device displays mg/dL or mmol/L, consistent tracking provides the insights you need to make informed decisions about your diabetes management.

A1C and Blood Sugar Units

Interestingly, A1C testing (which measures average blood sugar over 2-3 months) uses yet another unit: a percentage. However, A1C results can be translated to estimated average glucose (eAG) in either mg/dL or mmol/L:

• A1C 6% ≈ 126 mg/dL (7.0 mmol/L) average glucose
• A1C 7% ≈ 154 mg/dL (8.6 mmol/L) average glucose
• A1C 8% ≈ 183 mg/dL (10.2 mmol/L) average glucose
• A1C 9% ≈ 212 mg/dL (11.8 mmol/L) average glucose

This adds another layer to understanding your diabetes metrics. Our comprehensive A1C guide explains this relationship in detail.

The Future: Universal Standards?

While there have been discussions about standardizing blood glucose units globally, change happens slowly in healthcare. For the foreseeable future, both mg/dL and mmol/L will continue to be used.

The good news? Technology makes conversion seamless. Modern glucose monitoring apps, meters, and CGMs increasingly support both units with easy switching. As a person with diabetes, being fluent in both systems empowers you to access information and care anywhere in the world.