Molarity Calculator - Solution Concentration & Dilution

How to use this tool

1. Choose the "Molarity" or "Dilution" tab.
2. Enter the known values and leave the unknown field blank.
3. The result is displayed instantly.

Molarity formula

M = n / V where M is molarity (mol/L), n is the number of moles, and V is the final solution volume in litres. In the mass workflow, moles are calculated as mass (g) ÷ molar mass (g/mol), then divided by the same final volume. For example, 5.00 g of NaCl with a molar mass of 58.44 g/mol in 0.500 L gives about 0.1711 mol/L. The calculator accepts liters, milliliters, and microliters and converts them to liters internally.

Dilution formula

C₁V₁ = C₂V₂ - the amount of solute is conserved during a single dilution. C₁ and V₁ are the initial concentration and volume; C₂ and V₂ are the final concentration and volume. Enter any three values and leave one blank. V₁ and V₂ share one selected volume unit, so both volumes are converted consistently before solving.

Tips

Choose the Molarity tab to solve from moles or to calculate a mass from a target molarity, solution volume, and molar mass. Choose Dilution for a single-step stock-to-working-solution calculation. The selector beside each mode lets you enter L, mL, or µL directly.

• Volumes are converted to liters automatically; the displayed answer stays in your selected unit.
• To convert grams to moles, divide the mass in grams by the molar mass (g/mol) of the substance. Use the Molar Mass Calculator to look up molar mass from a chemical formula; enter its numeric result here.

Concentration units comparison

Making a standard solution (step-by-step)

To weigh a solute for a target solution, use the From mass workflow: enter the desired molarity, final volume, and the compound's molar mass, then leave solute mass blank. The calculator finds the mass using mass = M × V × molar mass. It handles the calculation only; the preparation steps below describe the usual measuring and mixing process.

1. Calculate the required mass using the From mass workflow above.
2. Weigh the solute precisely using an analytical balance.
3. Dissolve in ~80% of the final volume of solvent (usually distilled water) in a beaker.
4. Transfer to a volumetric flask: rinse the beaker 3 times with small amounts of solvent and add to the flask.
5. Add solvent to the calibration line: approach slowly with a wash bottle in the last few drops to hit the mark precisely.

Serial dilution background (not an interactive planner)

To prepare very dilute solutions, serial dilution is more accurate than a single large dilution. A 1:10 dilution (transfer 1 mL into 9 mL) repeated three times gives a final concentration of 1:1,000 of the original. This page's interactive dilution solver handles one step at a time and does not generate a serial-dilution plan. For n equal steps with dilution factor D = final volume ÷ transferred volume, the concentration after all steps is:

final concentration = starting concentration ÷ Dⁿ

For example, three 1:100 steps, each transferring 10 µL into a final volume of 1,000 µL, reduce a 1 M starting solution to 1 µM (10⁻⁶ M). Apply the single-step solver separately to each transfer if you need its individual concentrations.