Converting milligrams per litre (mg/L) to millimoles per litre (mmol/L) establishes the molecular weight of a substance in a litre. A gram (g) measures the absolute weight of a mass. A milligram is a measurement unit that represents 1/1000 of 1g. Thus, 1000mg are in 1g. A mole measures the amount of a substance or chemical in a mass. Conversely, 1mmol represents 1/1000 of 1 mole. Thus, 1000mmol are in 1 mole. Converting milligrams per litre (mg/L) into millimoles per litre requires completing a calculation based on the information you have for total milligrams and the molecular weight of the subject chemical.

- Skill level:
- Moderate

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### Things you need

- Chart of molecular weight
- Calculator

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## Instructions

- 1
Find the specific molecular weight, or moles, of your substance. For example, the molecular weight of blood sugar, or glucose, is 180.15588g/mol. A molecular weight calculator is linked in the Resources section.

- 2
Convert moles to millimoles. The conversion equation is 1(molecular weight)/ 1000 = mmol. Many diabetics use this equation to understand the milligrams to millimoles factor for glucose measurement. With the weight of glucose added, the equation is 1(180.15588)/1000 = 0.18015588mmol.

- 3
Convert millimoles to grams per unit. The equation for the calculation using glucose is 0.001mg/0.18015588 = 0.0055074 moles in each gram of the preferred liquid.

- 4
Place the numbers in the primary equation, and plug in your numbers. The equation is mg/L x (moles per gram of requested chemical x 10) = mmol/L.

The final equation to convert milligrams per litre to millimoles per litre, using the information found for glucose, is 1mg/L x (0.0055074 x10) = mmol/L.

#### Tips and warnings

- Use the correct units of measurement in calculations.