Concentration Calculator
Calculate molarity, solve dilution problems, and find percent composition — with step-by-step solutions.
Molarity (M = mol / L)
How It Works
Concentration describes how much solute is dissolved in a given amount of solution. The most common unit in chemistry is molarity (M), defined as moles of solute per liter of solution. To calculate molarity you need the mass of solute, its molar mass, and the solution volume.
The dilution equation C₁V₁ = C₂V₂ relates the concentration and volume before and after adding solvent. It works because the moles of solute stay constant — you're only changing the volume. Given any three of the four values, this calculator solves for the fourth.
Mass percent (w/w) expresses concentration as the mass of solute divided by the total mass of solution, multiplied by 100. It's commonly used in pharmacy, food science, and material preparation where volume measurements are impractical.
All three modes show the complete working so you can follow the algebra and check your homework. The molarity mode can auto-calculate molar mass from a chemical formula, saving you a separate calculation step.