Molarity Calculator
Molarity is the standard measure of solution concentration in chemistry, defined as the number of moles of solute dissolved per litre of solution (mol/L, written as M). It connects three measurable quantities: the mass of solute you weigh out (grams), the molar mass of that solute (g/mol), and the volume of solution you prepare (in mL or L). From those three inputs you can derive moles of solute (mass divided by molar mass), molarity (moles divided by volume in litres), mass concentration in g/L (moles per litre times molar mass), and concentration in mg/mL (numerically equal to g/L). Molarity is central to titration calculations, reaction stoichiometry, buffer preparation, and the dilution formula C1V1 = C2V2. This calculator handles the full chain: enter the mass of solute, its molar mass (use our molar mass calculator to find this), and the solution volume, and it instantly returns moles, molarity, g/L, and mg/mL. Volume can be entered in millilitres or litres. All inputs and outputs follow NIST SP 330 SI conventions.
Molarity: 0.0556 M (mol/L)
How molarity is calculated
Molarity is derived in two steps: first convert mass to moles using molar mass, then divide moles by volume in litres.
n (mol) = mass (g) / molar mass (g/mol)
M (mol/L) = n / V (L)
Concentration (g/L) = M x molar mass
Concentration (mg/mL) = g/L (numerically equal)
Worked example: 1 g NaCl in 300 mL water
- Molar mass of NaCl = 22.990 + 35.453 = 58.443 g/mol
- Moles = 1 g / 58.443 g/mol = 0.01711 mol
- Volume = 300 mL = 0.300 L
- Molarity = 0.01711 / 0.300 = 0.0570 M
- Concentration in g/L = 1 g / 0.300 L = 3.33 g/L
- Concentration in mg/mL = 1,000 mg / 300 mL = 3.33 mg/mL
Dilution formula
When diluting a solution, moles of solute are conserved. The dilution formula is:
C1 x V1 = C2 x V2
Where C1 and C2 are initial and final concentrations (in M) and V1, V2 are initial and final volumes. To make 500 mL of 0.1 M solution from a 1 M stock: V1 = (0.1 x 500) / 1 = 50 mL of stock, then add water to 500 mL total.
Common solution concentrations for reference
| Substance | Molar Mass (g/mol) | Mass for 1 M in 1 L |
|---|---|---|
| NaCl (sodium chloride) | 58.44 | 58.44 g |
| NaOH (sodium hydroxide) | 40.00 | 40.00 g |
| HCl (hydrochloric acid) | 36.46 | 36.46 g |
| H2SO4 (sulfuric acid) | 98.08 | 98.08 g |
| Glucose (C6H12O6) | 180.16 | 180.16 g |
| KCl (potassium chloride) | 74.55 | 74.55 g |
| CaCl2 (calcium chloride) | 110.98 | 110.98 g |
Mass figures assume anhydrous forms. Use the molar mass calculator to verify compound-specific values.
Molarity calculator: frequently asked questions
What is molarity?
Molarity (symbol M) is a measure of concentration defined as the number of moles of solute dissolved in one litre of solution. It is expressed in units of mol/L (or simply M). For example, a 1 M solution of sodium chloride (NaCl) contains 1 mole of NaCl (58.44 g) dissolved in enough water to make 1 litre of solution. Molarity is the most common concentration unit in chemistry and is fundamental to stoichiometry, titrations, and solution preparation.
What is the difference between molarity and molality?
Molarity (M) is moles of solute per litre of solution, so it depends on the total volume of the solution. Molality (m) is moles of solute per kilogram of solvent, so it depends on the mass of the solvent alone, not the total volume. Molality does not change with temperature (because mass is unaffected by thermal expansion), making it useful for boiling-point elevation and freezing-point depression calculations. Molarity is more convenient for volumetric work in the lab.
How do I prepare a 1 M solution?
To prepare a 1 M solution: (1) Calculate the molar mass of the solute. (2) Weigh out that mass in grams (for 1 M in 1 L: mass = molar mass in grams). (3) Dissolve the solute in a small amount of solvent. (4) Transfer to a volumetric flask and add solvent up to the calibration mark for your target volume. For example, to make 1 L of 1 M NaCl: weigh 58.44 g of NaCl, dissolve in ~700 mL of distilled water, then add water to reach exactly 1,000 mL.
What does a 1 M solution mean?
A 1 M (1 molar) solution contains 1 mole of solute dissolved in a total solution volume of 1 litre. Because one mole equals 6.02214076 x 10^23 molecules (Avogadro's number), a 1 M solution contains approximately 6.02 x 10^23 formula units per litre. The actual mass of solute per litre (in g/L) equals the molar mass of the substance, since molarity x molar mass = g/L when molarity = 1.
What is the dilution formula C1V1 = C2V2?
The dilution formula C1V1 = C2V2 states that when you dilute a solution, the number of moles of solute stays constant. C1 is the initial concentration, V1 is the initial volume, C2 is the final concentration, and V2 is the final volume. For example, to make 500 mL of 0.1 M HCl from a 1 M stock: V1 = (0.1 M x 500 mL) / 1 M = 50 mL. Take 50 mL of the 1 M stock and add water up to 500 mL total volume.
Official sources
- NIST Chemistry WebBook: webbook.nist.gov.
- NIST SP 330 (SI Units, 2019 edition): nist.gov SP 330.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology. For educational use only.