Blood Sugar Converter: Instantly Convert mg/dL and mmol/L
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Free blood sugar calculator
Convert mmol/L to mg/dL and mg/dL to mmol/L
Enter a blood glucose reading in either box. The calculator converts it instantly using the standard practical glucose conversion factor of 18.
mmol/L
Commonly used in the UK
mg/dL
Commonly used in the United States
Your conversion
Enter a value above
Both fields update automatically.
Try a common conversion:
Important: This calculator converts blood glucose units only. It does not interpret your result, set your target range or replace advice from your diabetes care team. Do not use it to change medication or insulin doses.
Quick answer
To convert mmol/L to mg/dL, multiply by 18. To convert mg/dL to mmol/L, divide by 18. For example, 5.8 mmol/L is 104.4 mg/dL, while 100 mg/dL is approximately 5.56 mmol/L.
Blood sugar conversion formulas
Blood glucose can be shown as millimoles per litre or milligrams per decilitre. These formulas let you convert the same glucose concentration between the two units:
mmol/L to mg/dL
mmol/L x 18 = mg/dL
Example: 7 mmol/L x 18 = 126 mg/dL.
mg/dL to mmol/L
mg/dL / 18 = mmol/L
Example: 180 mg/dL / 18 = 10 mmol/L.
The calculator keeps up to two decimal places for mmol/L and one decimal place for mg/dL. A glucose meter or clinical source may round the displayed result differently.
mmol/L to mg/dL conversion chart
Use this blood glucose conversion chart for a quick reference. These figures are unit conversions, not recommended target ranges.
mmol/L
mg/dL
mmol/L
mg/dL
2.0
36
7.0
126
3.0
54
7.8
140.4
3.5
63
8.0
144
4.0
72
9.0
162
4.5
81
10.0
180
5.0
90
11.0
198
5.5
99
11.1
199.8
5.6
100.8
12.0
216
5.8
104.4
15.0
270
6.0
108
20.0
360
What is the difference between mmol/L and mg/dL?
mmol/L
Millimoles per litre
This measures the number of glucose molecules in one litre of blood. It is the unit people most often see on glucose meters and health information in the UK.
mg/dL
Milligrams per decilitre
This measures the mass of glucose in one decilitre of blood. It is widely used in the United States and appears in many international articles and device reports.
The number looks different because the unit is different, but both describe the same blood glucose concentration. A result of 7 mmol/L and a result of 126 mg/dL are equivalent.
How to use a converted blood glucose result safely
Check the unit first. A value without its unit can be misunderstood.
Use the correct calculator. This factor applies to glucose, not cholesterol, ketones, HbA1c or other substances.
Keep the original reading. Record both the original number and unit when sharing a result with a healthcare professional.
Follow your personal plan. Target ranges and testing times vary by diabetes type, age, pregnancy, medication and individual circumstances.
Do not calculate insulin from this page. Use the method, device settings and advice provided by your diabetes care team.
A measured source of fast-acting carbohydrate
Keep a portable glucose option within reach
Each GlucoBoost 50ml bottle provides 15g of fast-acting carbohydrate in a ready-to-drink format. It is pre-measured, pocket-sized and made in the UK.
Multiply the mmol/L value by 18. For example, 6 mmol/L x 18 = 108 mg/dL. You can enter any value in the mmol/L box at the top of this page for an instant conversion.
How do I convert mg/dL to mmol/L?
Divide the mg/dL value by 18. For example, 90 mg/dL / 18 = 5 mmol/L. The calculator rounds mmol/L results to a maximum of two decimal places.
What is 5.8 mmol/L in mg/dL?
5.8 mmol/L is 104.4 mg/dL using the practical conversion factor of 18. A device may show the converted result as 104 mg/dL after rounding.
What is 100 mg/dL in mmol/L?
100 mg/dL is approximately 5.56 mmol/L. Some meters and reference charts may round this to 5.6 mmol/L.
What is 140 mg/dL in mmol/L?
140 mg/dL is approximately 7.78 mmol/L, usually rounded to 7.8 mmol/L.
Is mg/dL the same as mmol/L?
They are different units used to describe the same blood glucose concentration. mmol/L counts glucose molecules per litre, while mg/dL measures glucose mass per decilitre.
Can this calculator convert HbA1c?
No. HbA1c is reported as mmol/mol or a percentage and reflects average glucose over roughly two to three months. It requires a different calculation. This tool is only for a blood glucose reading shown in mmol/L or mg/dL.
What should I do if my blood sugar is below 4 mmol/L?
The NHS says low blood sugar is usually a reading below 4 mmol/L and should be treated quickly. Follow your agreed hypo treatment plan. If someone is unconscious or cannot swallow safely, do not give food or drink and seek emergency help.
Can I change the units on my blood glucose meter?
It depends on the meter. Some devices have fixed units to reduce the risk of confusion. Check the device manual or contact the manufacturer before changing any setting.
GlucoBoost products are designed to provide a fast-acting source of glucose. They are not intended to diagnose, treat, cure, or prevent any disease or medical condition.
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