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Molarity Calculator

Chemistry

Calculate the molarity of a solution from the mass of solute, its molar mass, and the volume of solution. Instant mol/L results with step-by-step working shown.

58.44 g
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58.44 g/mol
g/mol
1 L
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Molarity (mol/L)

1
Moles of Solute (mol)
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This calculator computes your Molarity (mol/L), Moles of Solute (mol) from the values you enter.

Inputs
Mass of SoluteMolar Mass of SoluteVolume of Solution
Outputs
Molarity (mol/L)Moles of Solute (mol)

What is a Molarity?

The Molarity Calculator computes the molar concentration of a solution — that is, how many moles of solute are present in every litre of solution. Molarity (symbol M) is the single most important concentration unit in chemistry because stoichiometry, reaction yields, and preparation of standard solutions all depend on it. Knowing the molarity of a reagent tells you exactly how many reacting particles you have in a given volume, which is essential for designing experiments and interpreting results.

In a laboratory, preparing a solution of known molarity is one of the first practical skills taught. You weigh out the required mass of solute, dissolve it, and then make up the volume precisely to the required level using a volumetric flask. The Molarity Calculator reverses this process or verifies it: enter the mass of solute in grams, the molar mass of the substance in g/mol, and the final volume of solution in litres to get the exact molarity in mol/L.

Indian chemistry students encounter molarity from Class 11 onwards (NCERT Chapter 1 — Some Basic Concepts of Chemistry) and it forms a central topic in JEE Main, JEE Advanced, and NEET preparation. Laboratory work for CBSE and ISC boards requires preparing solutions of precise concentrations — typically 0.1 M, 0.5 M, or 1 M — for acid-base and redox titrations.

Beyond academics, molarity is used in pharmaceutical manufacturing, food processing, water treatment plants, and biochemical research. Whenever a recipe calls for a "1 M phosphate buffer" or a "0.9% saline equivalent in molar terms," the underlying calculation is the one this tool performs. Related concentration measures include molality, which is preferred when temperature changes are involved, and mole fraction, which is used in vapour pressure and colligative property calculations.

How to use this Molarity calculator

  1. Enter the Mass of Solute — type the mass of the substance you have dissolved (or plan to dissolve) in the Mass of Solute field, in grams (g). For example, for NaCl enter 58.44.
  2. Enter the Molar Mass of Solute — type the molar mass of your substance in the Molar Mass of Solute field, in g/mol. For NaCl this is 58.44 g/mol; for glucose (C₆H₁₂O₆) it is 180.16 g/mol. Look up molar mass from the compound's formula and a periodic table.
  3. Enter the Volume of Solution — type the total volume of the prepared solution in the Volume of Solution field, in litres (L). If your volume is in millilitres, divide by 1000 first (e.g., 250 mL = 0.25 L).
  4. Read the results — the calculator instantly shows Molarity (mol/L) as the highlighted primary result and Moles of Solute (mol) as a secondary output.
  5. Check the step-by-step working — expand the steps panel to see the two calculation stages: grams → moles, then moles → molarity. This is useful for understanding the derivation or reproducing the working in a lab report or exam answer.
  6. Interpret and act — compare the calculated molarity against your target. If the molarity is too high, you need to use less solute or increase the volume. If too low, increase the mass of solute or reduce the final volume.

Formula & Methodology

Molarity is calculated in two steps:

Step 1 — Convert mass to moles:

> n = m ÷ M_r

Where:
- n = moles of solute (mol)
- m = mass of solute (g)
- M_r = molar mass of solute (g/mol)

Step 2 — Divide moles by volume:

> C = n ÷ V

Where:
- C = molarity (mol/L)
- n = moles of solute (mol)
- V = volume of solution (L)

Combined:

> C = m ÷ (M_r × V)

Worked example:

Prepare a solution by dissolving 29.22 g of NaCl (molar mass = 58.44 g/mol) in water to make 500 mL (0.5 L) of solution.

- n = 29.22 g ÷ 58.44 g/mol = 0.5 mol
- C = 0.5 mol ÷ 0.5 L = 1.0 mol/L (1 M)

This is a standard 1 M NaCl solution, one of the most commonly prepared solutions in chemistry and biology labs. Note that the volume refers to the final volume of the solution, not the volume of solvent added — always make up to volume in a calibrated volumetric flask, not simply add the solute to a fixed volume of water.

Frequently Asked Questions

Molarity is a measure of the concentration of a solute in a solution, expressed as the number of moles of solute per litre of solution. It is denoted by the symbol M and has the unit mol/L. Molarity is one of the most commonly used concentration units in chemistry because it directly relates to the number of reacting particles in a given volume, making stoichiometric calculations straightforward.
The molarity formula is M = n ÷ V, where M is molarity in mol/L, n is the number of moles of solute, and V is the volume of solution in litres. The number of moles is itself calculated as n = mass (g) ÷ molar mass (g/mol). Combining both steps gives the complete formula: M = mass ÷ (molar mass × volume).
Molarity (M) is defined as moles of solute per litre of solution, so its value changes with temperature because liquid volumes expand and contract with heat. Molality (m) is defined as moles of solute per kilogram of solvent, making it temperature-independent. For precise work involving temperature changes — such as boiling point elevation or freezing point depression — molality is preferred. Use the [Molality Calculator](/molality-calculator/) when the experiment involves temperature variation.
Molarity measures the total number of moles of solute per litre, whereas normality measures the number of equivalents of solute per litre. For acids and bases, the relationship is N = M × n, where n is the number of protons (acids) or hydroxide ions (bases) that the solute donates or accepts per formula unit. For a monoprotic acid like HCl, normality equals molarity; for H₂SO₄, normality is twice the molarity.
To convert grams to moles, divide the mass of the solute in grams by its molar mass in g/mol. For example, 58.44 g of NaCl divided by its molar mass of 58.44 g/mol gives exactly 1 mole. The Molarity Calculator performs this step automatically when you enter the mass of solute and molar mass. You can also use the [Grams to Moles Calculator](/grams-to-moles-calculator/) separately for a standalone conversion.
The molar mass of a compound is the sum of the atomic masses of all atoms in its chemical formula, expressed in g/mol. For example, water (H₂O) has a molar mass of 2(1.008) + 15.999 = 18.015 g/mol. Atomic masses are listed on the periodic table and are additive. The [Molar Mass Calculator](/molar-mass-calculator/) can automate this calculation once it is available.
Yes, the Molarity Calculator works for any solute as long as you know the mass dissolved and the molar mass of the substance. It is equally applicable to ionic compounds like NaCl, KCl, and CaCl₂, covalent compounds like glucose (C₆H₁₂O₆), and laboratory reagents like HCl or NaOH. Simply enter the correct molar mass for the substance you are working with.
A 1 molar solution (1 M) contains exactly 1 mole of solute dissolved in enough solvent to make 1 litre of solution. For example, a 1 M NaCl solution contains 58.44 g of NaCl per litre. This is a standard reference concentration used extensively in chemistry labs for preparing standard solutions, serial dilutions, and reaction mixtures.
Molarity is temperature-dependent because the volume of a liquid changes with temperature — solutions expand when heated and contract when cooled. As temperature rises, the same solution occupies a larger volume, reducing the molarity slightly. For experiments conducted at non-standard temperatures, it is best to either use molality (temperature-independent) or correct the volume measurement to a reference temperature.
In Indian school and college chemistry practicals (CBSE Class 11–12 and undergraduate labs), molarity is used extensively for preparing standard solutions for acid-base titrations, redox reactions, and volumetric analysis. Common standard solutions include 0.1 M HCl, 0.1 M NaOH, and 0.1 M Na₂CO₃. Understanding molarity is a core requirement for the CBSE and ICSE curricula as well as competitive exams like JEE and NEET.
After diluting a solution, use the dilution equation M₁V₁ = M₂V₂, where M₁ and V₁ are the initial molarity and volume, and M₂ and V₂ are the final molarity and volume. For example, diluting 50 mL of a 2 M NaCl solution to 200 mL gives a final molarity of (2 × 0.05) ÷ 0.2 = 0.5 M. You can verify this using the [Solution Dilution Calculator](/solution-dilution-calculator/) once it is available.
Molarity uses the unit mol/L, which is also written as M (capital M for molar). In SI notation it is sometimes expressed as mol·dm⁻³ since 1 dm³ equals 1 litre. All inputs to the Molarity Calculator should be in grams (for mass) and litres (for volume) to get the result in mol/L directly. If your volume is in millilitres, divide by 1000 before entering.
Also known as
molarity formulamoles per litresolution concentrationM calculatormol/L calculator