Blood glucose is measured differently around the world. The US, India, and a few other places use mg/dL milligrams per deciliter. The UK, Australia, Canada, and most of Europe use mmol/L millimoles per liter. That difference alone causes endless confusion. If you travel, talk to international doctors, or read studies from different countries, you need both units. So here is a straightforward converter that works instantly.
This converter is based on the standard formula recognized by the American Diabetes Association. One mmol/L equals approximately 18 mg/dL. To be exact, the factor is 18.0182, but 18 works fine for practical purposes. So 5.5 mmol/L times 18 gives 99 mg/dL. That is a normal fasting glucose. 7.8 mmol/L comes out to about 140 mg/dL, and 3.9 mmol/L gives 70 mg/dL. You get the idea.
I prefer keeping this calculator right here on the page instead of sending you out to some random site with pop up ads. That is especially important if you are on mobile. I have used too many converter tools that make you wait through a loading screen or redirect you somewhere else. This one does not do any of that. Just plug in your number and go.
You might be looking at your A1C test results, and what happens next is just as simple. The converter includes an A1C to eAG feature. If you know your A1C percentage, you can instantly see what your average blood sugar has been over the last two to three months. The American Diabetes Association recommends using eAG to help patients understand their A1C. It makes sense. You live with daily numbers, not percentages.
The formula for converting A1C to eAG is well established. For an A1C of 7 percent, the eAG is roughly 154 mg/dL or 8.6 mmol/L. Here is how that works. The math is 28.7 times your A1C minus 46.7 equals your eAG in mg/dL. Then divide by 18 to get mmol/L. That gives you a pretty accurate picture of your average glucose. If you track that number over time, it helps you spot trends before they become problems.
Over the past year, I have heard from quite a few readers who were confused by their blood sugar readings. One reader in Canada got a lab result showing 6.2 mmol/L but her phone app connected to her US based device showed 111 mg/dL. She did not know which one was right. Both were right. She just needed a converter. That is exactly why I put this together.
The numbers in the converter rely on standard medical thresholds. A normal fasting glucose for someone without diabetes is under 5.6 mmol/L or 100 mg/dL. Prediabetes is between 5.6 and 6.9 mmol/L or 100 to 125 mg/dL. Diabetes is 7.0 mmol/L or 126 mg/dL or higher. These thresholds come from the ADA and the World Health Organization. They have not changed in years, and they likely will not change anytime soon.
You can use this converter for any blood sugar number. It works for fasting glucose, post meal readings, random checks, or average values from your continuous glucose monitor. The calculator is not limited to any specific time of day or type of reading. So if you just had a meal spike and want to convert your reading, go ahead.
I personally like to check my numbers after meals. It gives me a real world sense of how my body handles different foods. But not everyone wants to do that. Some people just need to convert a single number their doctor gave them. That is fine too. The converter is simple enough for anyone to use.
If you want a tool that does more than just convert units, there are other options. I have tested a few. The Blood Sugar Unit Converter app on iOS was updated in June 2024, has a 4.3 star rating with 176 reviews, and works okay for basic conversions. But it forces you to watch an ad after almost every conversion, and if you want to remove ads, it asks for a credit card. That is a dealbreaker for me. I would rather use the web version.
There is also the Diabetes.co.uk converter, which has been around since 2019 and still works well. It does not have any flashy features, but it gets the job done without asking for anything. And if you like calculators in general, Omni Calculator has a whole suite of health tools including a blood sugar converter, an A1C calculator, a calorie calculator, and even a donut calculator because why not.
An important thing to remember is that conversion alone does not tell you what to do with your number. If your converted reading is high, you need to think about why. Did you eat something that spiked you? Are you stressed? Did you skip your medication? The converter answers the what, but you have to answer the why. Pay attention to patterns, not single readings.
The same goes for your A1C. It is a good measure of average control, but it is not perfect. People with anemia or kidney disease can get falsely low or falsely high A1C results. So if you have one of those conditions, do not rely on A1C alone. Use your daily glucose readings alongside it. And if your A1C does not match your home readings, ask your doctor about it.
One more thing about the converter. It works backward too. If you know your target range in one unit, you can enter the equivalent in the other. For example, if your doctor says keep your blood sugar under 7.0 mmol/L, that is 126 mg/dL. If your meter shows 140 mg/dL, you know you are a bit over. The converter lets you internalize those numbers until they become second nature. After a while, you will not even need the tool.
You might be trying to improve your numbers through diet, exercise, or medication. If weight management is part of your plan, this is a good time to think about how your blood sugar and weight intersect. Many people with type 2 diabetes find that losing even 5 to 10 percent of their body weight improves their blood sugar control significantly. For those dealing with insulin resistance, learning about losing weight with insulin resistance can help you choose a strategy that works with your body's biology rather than against it. A lot of the same lifestyle changes that stabilize glucose also support sustainable weight loss.
I also get asked whether the converter works for gestational diabetes, which is a blood sugar condition that affects pregnant women. Yes, it does. Gestational diabetes uses the same units and the same conversion factor. But your target ranges may be stricter than typical type 2 diabetes targets. Always follow your doctor's specific targets for gestational diabetes.
For people managing prediabetes, the converter can help you stay on track. If you see your post meal number going over 140 mg/dL 7.8 mmol/L regularly, you are heading in the wrong direction. That is a sign that your body is having trouble handling sugar. The converter helps you spot that pattern before it becomes full blown diabetes.
I built this converter to be fast and accurate. It runs entirely on the page without any extra software. You do not need to install anything or create an account. I hate sites that make you jump through hoops to use a simple calculator. This one is direct. Put in a number, pick your unit, get your result.
Let me walk you through a real example. Say your blood sugar is 180 mg/dL. You want to know what that is in mmol/L. You click mmol/L, enter 180, and the converter gives you 10.0 mmol/L. That is a high reading, meaning your blood sugar is above the typical target range. If you were aiming for under 7.8 mmol/L after meals, you know you need to figure out what caused the spike. Was it the rice? The pasta? The stress? The converter does not answer that, but it gives you a clear number to work with.
Another example. Your A1C comes back at 6.5 percent. The eAG ends up around 140 mg/dL or 7.8 mmol/L. That is at the top end of where you want to be. If it goes up further, you might need to adjust your medication or diet. The converter helps you see that trajectory.
If you regularly track your numbers, I recommend keeping a log. Write down the date, your reading in either unit, and any notes about what you ate or how you felt. Over time, that log becomes way more useful than any single number. It shows you patterns. And the converter makes it possible to keep your log in one unit even if your meter uses another.
Some meters let you change the unit in the settings. If yours does, you can set it to whichever unit you prefer and avoid conversion altogether. But not all meters have that option. And even if yours does, you might still need to read results from a doctor's office that uses a different unit. That is why a converter is still handy.
I have made this converter accessible from both desktop and mobile. The layout adjusts so it works on any screen size. I tested it on a few browsers and it came out fine across the board. If you notice any issues, let me know.
And if you are newly diagnosed and overwhelmed by all the numbers, you are not alone. It takes time to learn what your readings mean. Use the converter as many times as you need. It will not judge you. After a week or two, you will start to memorize the key numbers. You will know that 5.5 is normal, 7.8 is borderline, and 10 is high. But until that happens, keep the converter handy.
I put together a FAQ section below because everyone asks the same questions. I covered the most common ones. If you have a question that is not here, check with your doctor. They know your specific health situation better.
Frequently Asked Questions
What is the formula for blood sugar conversion?
The standard formula is mg/dL divided by 18 equals mmol/L. To go the other way, mmol/L times 18 equals mg/dL. The exact factor is 18.0182, but 18 works for daily use.
How do I convert my A1C to average blood sugar?
Use the formula 28.7 times your A1C minus 46.7 to get your eAG in mg/dL. Then divide by 18 for mmol/L. Or just use the converter on this page.
Which countries use mg/dL versus mmol/L?
The US, India, China, and parts of the Middle East use mg/dL. The UK, Australia, Canada, and most of Europe use mmol/L. Always check which unit your lab uses.
Is the conversion the same for type 1 and type 2 diabetes?
Yes. The conversion factor is the same regardless of diabetes type. But target ranges may differ depending on your age, pregnancy status, and other factors.
Can I trust an online converter for medical decisions?
This converter uses the standard medical formula, but do not make medication changes based solely on a conversion. Talk to your doctor first. Blood sugar management is too important to rely on a single tool.
Do you have a mobile app?
Not yet, but the web version works perfectly on mobile. Just bookmark it and you are set.
Is there a limit to how high or low the converter works?
No. It works for any number you enter. But for extreme values, call your doctor or seek emergency care. The converter gives a number, but it does not give medical advice.
I have type 2 diabetes. Should I focus on blood sugar control or weight first?
Both are linked, and improving one usually helps the other. If you are ready to make changes, exploring weight loss strategies tied to type 2 diabetes can be a solid starting point. Many people see their glucose numbers improve significantly after shedding some weight. It might be worth looking into.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before making any changes to your diabetes management plan. Individual blood sugar targets may vary based on age, overall health, and other factors. The converter tool on this page is based on standard medical formulas but should not replace professional medical guidance. Affiliate links are included in this article for products discussed, at no extra cost to you. We only recommend products we have personally tested and found useful. This article was last updated in June 2025.
