Molarity & Solution Concentration Calculator

Calculate molarity (M), solute mass (g), or solution volume (L) using M = n / V. Includes molecular weight lookups for common reagents, millimolar conversions, and dilution prep breakdown.

Target Parameter

Live calculation
g/mol
Quick Sample Presets
grams (g)
Liters (L)
Calculated Molarity
1.0000 Mvia M = m / (MW × V)
Total Solute Amount1.0000 moles

Millimolar (mM)

1,000 mM

Micromolar (µM)

1.00e+6 µM

Concentration (g/L)

58.44 g/L

Volume (mL)

1000.0 mL

Laboratory Preparation Recipe

1. Weigh exactly 58.440 grams of solute (MW = 58.44 g/mol).

2. Transfer the solute into a clean volumetric flask or beaker.

3. Add solvent (e.g. deionized H₂O) until dissolved, then bring total volume up to exactly 1000 mL (1.000 L).

This solution contains 1.0000 moles of solute in 1.00 L of solvent.

The final concentration is 1.0000 M (1000.0 mM), containing 58.44 grams of dissolved solute per liter.

The Fundamentals of Chemical Concentration ($M = n / V$)

In analytical chemistry and biochemistry, molarity ($M$) is the ubiquitous standard measure of solute concentration. Defined as the number of moles ($n$) of a chemical entity dissolved per liter ($V$) of solution, molarity connects macroscopic mass on a lab scale to microscopic stoichiometry.

Molarity & Solution Stoichiometry Formulas
1. Solve Molarity (M)
M =
m (mass in g)MW × V (Liters)

mol/L = grams ÷ (MW × Liters)

2. Solve Required Mass (m)
m = M × MW × V

grams = Molarity × MW × Liters

3. Solve Solution Volume (V)
V =
m (mass in g)MW × M

Liters = grams ÷ (MW × Molarity)

Stock Solution Dilution Equation
M₁V₁ = M₂V₂|1 M = 1,000 mM = 1,000,000 µM|1 g/L = 1,000 ppm (aqueous)
Step-by-Step Calculation Breakdown
Example 1: Preparing 500 mL of 0.50 M Sodium Chloride (NaCl, MW = 58.44 g/mol)
1. Parameters: Molarity M = 0.50 M, Volume V = 0.500 L, Molar Mass MW = 58.44 g/mol
2. Calculate required moles: n = 0.50 mol/L × 0.500 L = 0.250 moles
3. Calculate mass: m = 0.250 mol × 58.44 g/mol = 14.61 grams of NaCl
Example 2: Dissolving 90.08 g of Glucose (C₆H₁₂O₆, MW = 180.16 g/mol) into 1.0 L
1. Parameters: Mass m = 90.08 g, Volume V = 1.00 L, MW = 180.16 g/mol
2. Calculate moles: n = 90.08 ÷ 180.16 = 0.500 moles
3. Compute molarity: M = 0.500 mol ÷ 1.00 L = 0.500 M (500.00 mM)

Common Chemical Reagents & Molar Masses

Compound NameChemical FormulaMolar Mass (g/mol)Laboratory Role
Sodium Chloride (Table Salt)NaCl58.44Standard physiological saline solute
Glucose (Dextrose)C₆H₁₂O₆180.16Cellular energy carbohydrate solute
Sodium Hydroxide (Lye)NaOH40.00Strong base for titrations and saponification
Hydrochloric AcidHCl36.46Strong monoprotic mineral acid
Sulfuric AcidH₂SO₄98.08Diprotic industrial acid
EthanolC₂H₅OH46.07Biofuel and universal solvent
Calcium CarbonateCaCO₃100.09Limestone and antacid buffering mineral
Potassium PermanganateKMnO₄158.03Powerful oxidizing agent in redox titrations
AmmoniaNH₃17.03Weak base and agricultural nitrogen source
Sucrose (Table Sugar)C₁₂H₂₂O₁₁342.30Disaccharide sweetening agent
Copper(II) SulfateCuSO₄159.61Blue crystalline agricultural fungicide
Sodium BicarbonateNaHCO₃84.01Baking soda & biological buffer

Frequently Asked Questions

What is molarity (M) and how is it calculated?
Molarity (M) is the chemical concentration of a solution expressed as the number of moles of solute dissolved per liter of total solution: M = n / V = mass / (MW × V). A 1.0 M solution contains 1 mole of solute dissolved in enough solvent to yield exactly 1.0 liter of finished solution.
What is the difference between molarity (M) and molality (m)?
Molarity (M) measures moles of solute per liter of total solution, which slightly changes with temperature due to liquid thermal expansion. Molality (m) measures moles of solute per kilogram of solvent mass, which is completely temperature-independent and preferred for colligative properties.
How do you calculate the mass needed to prepare a specific molarity?
Multiply the desired molar concentration (M, in mol/L) by the molecular weight of the solute (MW, in g/mol) and the final target solution volume (V, in Liters): Mass (g) = M × MW × V.
How do you dilute a concentrated stock solution?
Use the dilution conservation equation: C₁V₁ = C₂V₂ (or M₁V₁ = M₂V₂), where M₁ and V₁ are the initial stock concentration and volume, and M₂ and V₂ are the desired final concentration and volume.

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