Molarity Calculator (g/mL and g/L to Molarity)
Convert grams, g/mL or g/L to molarity. Calculate moles, concentration and millimoles from mass and volume.
Molarity is the number of moles of solute per liter of solution - the most common concentration unit in chemistry. This calculator handles three common workflows: converting grams to molarity (mass / molar mass / volume), converting g/mL to molarity (mass density × 1000 / molar mass), and converting g/L to molarity (concentration / molar mass). Enter your mass, molar mass and volume to get moles, molarity and concentration in g/L.
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Frequently asked questions
Multiply by 1000 to get g/L, then divide by molar mass. Example: 1.84 g/mL of pure sulfuric acid (H2SO4, molar mass 98.08 g/mol) = 1840 g/L ÷ 98.08 = 18.76 M. For dilute solutions, multiply by the mass percent first.
Divide concentration in g/L by molar mass in g/mol. Example: 40 g/L of NaOH (molar mass 40 g/mol) = 1 M. 58.44 g/L of NaCl = 1 M. The unit g/L cancels with g/mol to leave mol/L = M.
Use volume = moles / molarity, then multiply by 1000. Example: to get 0.05 mol from a 0.5 M solution, you need 0.05 / 0.5 = 0.1 L = 100 mL. To dilute, use C1V1 = C2V2 instead.
Dissolve 58.44 g of NaCl (one molar mass) in enough water to make exactly 1 liter of solution. The molar mass of NaCl is 22.99 + 35.45 = 58.44 g/mol. For 100 mL of 1 M, use 5.844 g.
Molarity (M) is moles per liter of solution. Molality (m) is moles per kilogram of solvent. Molality is temperature-independent because it uses mass, not volume - useful for boiling point and freezing point calculations.