You enter the moles of solute and the volume of solution in liters, milliliters, or microliters. The tool converts the volume to liters, then divides moles by liters to get molarity (M). It also reports millimolarity (M × 1,000) and the total amount in millimoles (moles × 1,000). It assumes a homogeneous solution at standard conditions and does not account for activity coefficients or temperature effects.
Molarity (M) is moles of solute per liter of solution. Molality (m) is moles of solute per kilogram of solvent. Molality doesn't change with temperature because mass doesn't expand, while molarity can shift slightly as the solution's volume changes with temperature.
This calculator finds molarity from moles and volume. For dilutions, use the formula C₁V₁ = C₂V₂ — multiply your starting concentration by starting volume to get the moles, then divide by the new volume.
Divide the mass in grams by the substance's molar mass (g/mol). For example, 58.44 g of NaCl ÷ 58.44 g/mol = 1 mol. Use the molecular weight calculator to find the molar mass.
Molarity is defined per liter. If you measure volume in milliliters or microliters, the calculator converts to liters first. Entering 500 mL is the same as 0.5 L — the result is the same, but forgetting to convert is a common lab error.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.