Science 2026-05-04 3 min read By Konvertibly Team

Concentration Calculator: Molarity, Molality, and Dilution

Calculate solution concentration as molarity (mol/L), molality (mol/kg), and percentage. Use the dilution formula C₁V₁ = C₂V₂ for lab dilutions.

Solution Concentration

Concentration expresses how much solute is dissolved in a given amount of solution or solvent. The right unit depends on whether you're doing colligative properties, reactions, or lab dilutions.

Molarity (M)

M = n / V
n = moles of solute
V = volume of solution (L)

25g NaCl (M=58.44) in 500mL:
n = 25/58.44 = 0.428 mol
M = 0.428/0.5 = 0.856 M

Dilution Formula

C₁V₁ = C₂V₂
C₁ = initial concentration
V₁ = volume taken
C₂ = final concentration
V₂ = final volume

Dilute 10 mL of 6M HCl to 0.1M:
V₂ = C₁V₁/C₂ = 6×10/0.1 = 600 mL
(Add 10mL stock to 590mL water)

Other Concentration Expressions

Molality: m = n / mass_solvent (mol/kg)  (temp-independent)
% w/v:    g solute / 100 mL solution × 100
% w/w:    g solute / g solution × 100
ppm:      mg solute / L solution (dilute aqueous)

Calculate concentrations: Free Concentration Calculator