Molarity Calculator
Calculate molarity (concentration in mol/L) from the mass of solute, its molar mass, and the volume of solution.
How to use this molarity calculator
- Enter the mass of your solute in grams.
- Enter the molar mass (use the Molar Mass Calculator if needed).
- Enter the total volume of solution in millilitres.
- Read off molarity in mol/L (M) and moles.
Formula
Moles = mass ÷ molar mass. Molarity (M) = moles ÷ volume (L). Example: 58.44 g NaCl in 1 L → 1.000 M.
About the Molarity Calculator
Molarity is the most commonly used concentration unit in chemistry. When a protocol calls for '2 M HCl', it means 2 moles of HCl per litre of solution.
To prepare a solution: grams needed = molarity × volume(L) × molar mass. For 500 mL of 0.5 M glucose (M=180.16): 0.5 × 0.5 × 180.16 = 45.04 g, dissolved and brought to the 500 mL mark.
Frequently asked questions
+What is molarity?
Molarity (M) is the number of moles of solute per litre of solution. A 1 M NaCl solution contains 58.44 g of NaCl dissolved in enough water to make 1 litre total.
+Molarity vs molality?
Molarity (M) is moles per litre of solution. Molality (m) is moles per kilogram of solvent. Molality is temperature-independent; molarity changes slightly as density changes.
+How do I make 0.1 M NaCl?
Dissolve 5.844 g NaCl (molar mass 58.44) in water, then top up to exactly 1000 mL in a volumetric flask.