Molarity Calculator
Find solution concentration from moles and volume.
Results update as you type.
How it works
Molarity is the workhorse concentration unit of chemistry, and this molarity calculator returns it instantly from the moles of solute and the volume of solution you enter. Reported in moles per litre, molarity tells you exactly how many particles of a dissolved substance sit in each litre of liquid, which is the figure most reactions, titrations, and dilution problems demand. Understanding molarity matters because reaction stoichiometry is counted in particles, not grams. Two solutions of equal molarity contain the same number of reactive units per litre even when their masses differ wildly, so a chemist reaching for a molarity calculator can predict how much of one reagent will neutralise or combine with another. It underpins everything from preparing a buffer to dosing a reagent in industry. The formula works because molarity is simply moles divided by litres, an intensive ratio that stays constant no matter how much solution you scoop out. Students, lab technicians, pharmacists, and researchers all rely on a molarity calculator to prepare standard solutions accurately, avoid arithmetic slips, and move quickly between concentration, volume, and amount of substance when planning an experiment.
M = moles ÷ volume (L)
Molarity expresses concentration as the number of moles of solute dissolved in each litre of solution, so dividing total moles by total volume gives the amount of substance packed into a unit of liquid. The formula works because moles count the actual number of particles present while litres measure the space they occupy, and their ratio stays fixed for a well-mixed homogeneous solution. That constant ratio is what lets chemists scale a recipe up or down while keeping reactivity the same.
Source:Standard chemistry (molar concentration)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter moles of solute and solution volume.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Molarity updates instantly as you type — no button to press.
Frequently asked questions
What units should I enter for moles and volume?
Enter the amount of solute in moles and the total solution volume in litres, and the result comes out directly in moles per litre, the standard unit of molarity. If your volume is in millilitres, divide by 1,000 first, because 1,000 mL equals one litre. Keeping to moles and litres guarantees the concentration figure matches the values printed on reagent bottles and textbook tables.
How do I convert grams of solute into moles?
Divide the mass in grams by the substance's molar mass in grams per mole, which you read off the periodic table by summing the atomic masses in the formula. For example, sodium chloride has a molar mass near 58.44 g/mol, so 58.44 g equals one mole. Once you have moles, enter that figure here along with the volume to obtain molarity.
What is the difference between molarity and molality?
Molarity divides moles of solute by litres of solution, while molality divides moles of solute by kilograms of solvent. Molarity is easier to measure with volumetric glassware but shifts slightly with temperature because liquids expand. Molality ignores temperature entirely since mass does not change. For most bench chemistry and titrations, molarity is the practical choice this calculator provides.
Why does molarity change when I add more water?
Adding water increases the solution volume while the number of moles of solute stays the same, so the ratio of moles to litres falls and the solution becomes more dilute. This is the basis of the dilution equation M1V1 = M2V2. If you want a specific target molarity, calculate the final volume needed and top up carefully to that mark.
Can molarity be greater than one?
Yes. A molarity above one simply means more than one mole of solute is dissolved per litre of solution, which is common for concentrated acids and stock reagents. Concentrated hydrochloric acid, for instance, is around 12 M. The upper limit is set by the substance's solubility, the point at which no more solute will dissolve and any excess settles out as solid.