CalcVind

Molarity Calculator

Molarity, mass to weigh out, or a dilution

Your Solution

Mass to Dissolve

1.461 gWeigh out
0.025 mol
Moles
58.44 g/mol
Molar mass
5.844 g/L
Concentration

Working

  1. Moles = molarity × volume (L)
  2. = 0.1 × 0.25 = 0.025 mol
  3. Mass = moles × molar mass = 0.025 × 58.44 = 1.461 g
  1. 1
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  2. 2
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  3. 3
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What is the molarity formula?

Molarity (M) is moles of solute per litre of solution. Moles come from the mass divided by the molar mass.

Molarity = moles ÷ litres of solution

Moles = mass (g) ÷ molar mass (g/mol)

Dilution: C₁V₁ = C₂V₂

Making up a solution

Weigh the solute, dissolve it in less water than you need, then add water up to the final volume in a volumetric flask. Volume of solution, not volume of water added, is what counts.

Hydrated salts

Use the molar mass of the form you weigh. Copper sulphate crystals are CuSO₄·5H₂O (249.69 g/mol), not anhydrous CuSO₄ (159.61 g/mol), so you need more of them for the same molarity.

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Frequently asked questions

How many grams of NaCl make 250 mL of 0.1 M solution?

1.461 g. Moles = 0.1 × 0.25 = 0.025 mol, and 0.025 × 58.44 g/mol = 1.461 g.

What is the difference between molarity and molality?

Molarity is moles per litre of solution; molality is moles per kilogram of solvent. Molality doesn't change with temperature, molarity does slightly.

How do I dilute 1 M to 0.1 M?

For 250 mL of 0.1 M, take 25 mL of the 1 M stock and add water up to 250 mL, a tenfold dilution.

Last reviewed: October 2026