What Is the Molarity to mg/mL Calculator?
This tool converts a solution's molar concentration (molarity, in mol/L or M) into a mass concentration expressed in milligrams per milliliter (mg/mL). It is a universal chemistry conversion useful for biology, biochemistry, pharmacology, and any lab where you prepare or dose solutions. All you need is the molarity and the molecular weight (molar mass) of the compound.
How to Use It
Enter the molarity in mol/L and the molecular weight in g/mol. The calculator returns the concentration in mg/mL and also in µg/mL. For example, a 0.1 M glucose solution (MW 180.16 g/mol) gives 18.016 mg/mL.
The Formula Explained
The conversion comes directly from the definition of molarity. Molarity is moles of solute per liter of solution. Multiplying by molecular weight (grams per mole) gives grams per liter:
$$\text{g/L} = \text{M} \times \text{MW}$$
Since 1 g/L equals 1 mg/mL (because grams→mg multiplies by 1000 and liters→mL divides by 1000, the factors cancel), the result simplifies to:
$$\text{mg/mL} = \text{M} \times \text{MW}$$
Worked Example
Suppose you have a 0.5 M solution of sodium chloride (NaCl), whose molecular weight is 58.44 g/mol. The concentration is $$0.5 \times 58.44 = 29.22 \text{ mg/mL},$$ or 29,220 µg/mL.
FAQ
Is mg/mL the same as g/L? Yes — numerically they are identical, so \(\text{M} \times \text{MW}\) gives both at once.
Where do I find molecular weight? It is the sum of atomic weights of all atoms in the molecule, listed on the chemical's datasheet or container label.
How do I go from mg/mL back to molarity? Divide the mg/mL value by the molecular weight: \(\text{M} = (\text{mg/mL}) \div \text{MW}\).
