Blood Sugar Converter
Convert blood glucose between mg/dL and mmol/L, then see a clear context note for fasting, before-meal, after-meal, random, or 2-hour glucose test readings.
What this blood sugar converter does
The Blood Sugar Converter changes a glucose result between the two common unit systems: mg/dL and mmol/L. Many glucose meters, continuous glucose monitors, lab reports, and diabetes education materials use different units depending on country or device setting. This tool lets you enter one value and instantly see the matching value in the other unit.
The conversion is specific to glucose. That matters because mmol/L is based on the amount of glucose molecules, while mg/dL is based on the mass of glucose in blood. The calculator uses the standard glucose conversion factor: mmol/L to mg/dL is multiplied by 18.018, and mg/dL to mmol/L is multiplied by 0.0555.
A converter is helpful when you read a foreign lab report, compare online diabetes resources, travel with a meter set to another unit, or share readings with someone in a different country. It also lowers the chance of confusing a value like 7.0 mmol/L with 70 mg/dL, which would mean very different things.
Blood sugar conversion formulas
mg/dL to mmol/L
mmol/L = mg/dL ร 0.0555
Example: 126 mg/dL ร 0.0555 = about 7.0 mmol/L. This is why 126 mg/dL and 7.0 mmol/L describe the same glucose concentration in different units.
mmol/L to mg/dL
mg/dL = mmol/L ร 18.018
Example: 10.0 mmol/L ร 18.018 = about 180 mg/dL. Many quick charts round the factor to 18 for easier mental math.
Fast mental shortcut
mg/dL รท 18 โ mmol/L
The shortcut is good for quick understanding. The calculator uses the more exact factor so the displayed values are cleaner for logs and notes.
Why cholesterol uses a different factor
Do not reuse glucose math for cholesterol
Cholesterol and glucose have different molecular weights, so mmol/L conversions are not interchangeable. This converter is built for blood glucose only.
How to read fasting blood sugar
Fasting blood sugar is usually measured after not eating overnight. For general screening, a fasting value below 100 mg/dL is commonly treated as a normal range. A value from 100 to 125 mg/dL falls in a prediabetes range, and 126 mg/dL or higher is in a diabetes-range result that needs confirmation with proper testing.
In mmol/L, those same guide points are about 5.6 mmol/L and 7.0 mmol/L. That means a fasting reading of 6.1 mmol/L is not โsix blood sugar pointsโ in the mg/dL sense; it is about 110 mg/dL. The converter makes this difference easier to see.
A fasting result should be read with the full clinical picture. Stress, illness, medicines, recent food, sleep, pregnancy, and lab timing can all affect glucose. A healthcare professional may repeat the test, check A1C, or order a glucose tolerance test when the result is unclear.
Before-meal and after-meal readings
People monitoring diabetes often use target ranges instead of diagnosis ranges. A common before-meal target is 80 to 130 mg/dL, which is about 4.4 to 7.2 mmol/L. A common after-meal target is below 180 mg/dL, or below about 10.0 mmol/L, measured around two hours after the start of a meal.
These targets are not the right target for every person. Children, older adults, pregnant people, people with frequent low blood sugar, and people using insulin may have different targets. Use the calculator for conversion and general context, then follow the target range set by your own care team.
| Context | mg/dL guide | mmol/L guide |
|---|---|---|
| Low blood sugar line | Below 70 | Below 3.9 |
| Common before-meal diabetes target | 80-130 | 4.4-7.2 |
| Common after-meal diabetes target | Below 180 | Below 10.0 |
| Fasting prediabetes range | 100-125 | 5.6-6.9 |
| Fasting diabetes-range result | 126 or higher | 7.0 or higher |
Worked examples
Example 1: Convert 100 mg/dL to mmol/L
100 ร 0.0555 = 5.55 mmol/L. Rounded for daily use, 100 mg/dL is about 5.6 mmol/L. This is the point where a fasting reading begins to move out of the usual normal fasting range in many screening guides.
Example 2: Convert 7.8 mmol/L to mg/dL
7.8 ร 18.018 = about 141 mg/dL. If this is a two-hour glucose tolerance test result, it sits around the lower edge of the prediabetes range. If it is a random home check, the meaning depends on timing, food, medication, symptoms, and your personal targets.
Example 3: Convert 10.0 mmol/L to mg/dL
10.0 ร 18.018 = about 180 mg/dL. This is a common after-meal target line for many people with diabetes, but not a universal target for every person.
Using blood sugar results with health planning
Blood sugar is affected by food, activity, stress, sleep, illness, medication, and body weight. If your readings are often higher than your target, calorie planning may be part of the broader discussion. The calorie calculator can help estimate daily calorie needs, while the maintenance calorie calculator helps you understand the calorie level that may keep weight stable.
Weight is not the only factor in blood glucose control, but it can be relevant for some people. The ideal weight calculator gives a height-based reference point. Use it as context only, not as a diagnosis or a strict target.
Fat intake also matters when building meals because higher-fat meals can slow digestion and may change the timing of glucose rise for some people. The fat intake calculator can help set a daily fat gram target from calories. For diabetes meal planning, total carbohydrates, fiber, protein, fat quality, and timing all matter.
When a blood sugar reading needs attention
A converter cannot tell you what action to take in every situation. Very low glucose, symptoms of low blood sugar, very high readings, repeated high readings, pregnancy, illness, vomiting, ketones, chest pain, confusion, or shortness of breath need medical guidance. If you use insulin or medications that can cause low blood sugar, follow the low-glucose action plan provided by your healthcare team.
- Below 70 mg/dL: often treated as low blood sugar, especially for people using insulin or certain diabetes medicines.
- Below 54 mg/dL: a more serious low range that should be handled according to your care plan.
- Repeated high readings: should be discussed with a clinician, especially when paired with thirst, frequent urination, fatigue, blurry vision, or weight loss.
- One reading is not a diagnosis: proper diagnosis depends on testing method, timing, repeat confirmation, and clinical review.
Blood sugar converter โ FAQ
How do I convert blood sugar from mg/dL to mmol/L?
To convert blood sugar from mg/dL to mmol/L, multiply the mg/dL value by 0.0555. A common shortcut is to divide mg/dL by 18. For example, 126 mg/dL is about 7.0 mmol/L.
How do I convert blood sugar from mmol/L to mg/dL?
To convert blood sugar from mmol/L to mg/dL, multiply the mmol/L value by 18.018. A common everyday shortcut is to multiply by 18. For example, 7.0 mmol/L is about 126 mg/dL.
Why do some countries use mg/dL and others use mmol/L?
mg/dL measures the mass of glucose in a deciliter of blood, while mmol/L measures the amount of glucose molecules in a liter of blood. The United States commonly uses mg/dL, while many other countries use mmol/L. The result describes the same blood glucose level in different units.
What is a normal fasting blood sugar?
For general screening, fasting blood sugar below 100 mg/dL is often listed as normal, 100 to 125 mg/dL as a prediabetes range, and 126 mg/dL or higher as a diabetes-range result that needs confirmation with proper testing. One reading alone is not a diagnosis.
What is a common blood sugar target for people with diabetes?
Common diabetes targets are often 80 to 130 mg/dL before meals and below 180 mg/dL about two hours after the start of a meal. Individual targets can be different based on age, pregnancy, medication, risk of low blood sugar, and other health conditions.
What blood sugar level is considered low?
A blood sugar reading below 70 mg/dL, or below 3.9 mmol/L, is commonly treated as low blood sugar. A reading below 54 mg/dL, or below 3.0 mmol/L, is a more serious low range. Follow the care plan given by your healthcare team if you are at risk of hypoglycemia.
Can this converter diagnose diabetes?
No. This calculator converts units and gives general context only. Diabetes diagnosis requires proper testing and review by a qualified healthcare professional. Symptoms, fasting status, medications, pregnancy, illness, and test type all matter.
This calculator is for educational purposes only. It is not medical advice. Always consult a qualified doctor or health professional before making health decisions.
