Molarity Calculator
Convert solute quantity and solution volume into molar concentration with laboratory-ready precision.
If you know the number of moles directly, enter it here.
Required when the solute mass is entered in grams. Optional when moles are provided.
Final volume of the solution after dilution.
Automatically converted to liters.
How to Use This Calculator
Gather solution information
Determine the amount of solute, its molar mass if you are using grams, and the final solution volume.
Enter solute data
Choose whether you know the solute in moles or grams and provide the corresponding values.
Specify solution volume
Enter the final volume and select the unit. The tool converts everything to liters.
Calculate and interpret
Press the button to see molarity plus supporting conversions and prep guidance.
Formula
M = n / V = (m / Mr) / V
M is molarity (mol L^-1), n is moles of solute, m is mass in grams, Mr is molar mass (g mol^-1), V is solution volume in liters.
Example: 5.85 g NaCl in 250 mL solution
m = 5.85 g, Mr = 58.44 g mol^-1, V = 0.250 L
n = 5.85 / 58.44 = 0.100 mol
M = 0.100 / 0.250 = 0.400 mol L^-1
Tip: Always use the final solution volume after mixing. Top up to the mark in a volumetric flask for best accuracy.
Full Description
Molarity is the go-to concentration unit in chemistry labs, QA environments, and classrooms. This calculator streamlines the process by unifying solute amount and volume inputs, handling unit conversions behind the scenes, and presenting a clear mol/L result alongside helpful supporting values.
Whether you are standardising reagents or teaching solution preparation, the tool guides you through each step. It accepts moles directly from stoichiometric work or converts grams to moles when the molar mass is known. Summary cards reinforce best practices such as targeting the final solution volume, not just the solvent volume.
Ideal for
- Academic labs: Verify concentrations for titrations, spectroscopy, and analytical experiments.
- Quality assurance: Confirm reagent strengths before release.
- Research workflows: Prepare stock solutions for assays, cell culture, or materials research.
- Teaching: Demonstrate the relationship between mass, moles, and volume.
- Home chemistry: Translate recipes into precise molar terms.
Why it helps
- ✅ Unit conversion: Accepts common volume units and converts to liters.
- ✅ Flexible inputs: Works with moles or grams and back-calculates when partial data is supplied.
- ✅ Preparation guidance: Supplies a plain-language mixing tip based on the results.
- ✅ Error checks: Flags impossible or zero values before you commit to an experiment.
- ✅ Responsive layout: Easy to use at the bench on any device.
Frequently Asked Questions
Do I use solvent volume or final solution volume?
Always use the final solution volume after all components are mixed and the flask is topped to the mark.
What if I only know the solute mass?
Choose grams as the input type, enter the mass and molar mass, and the calculator converts to moles before computing molarity.
Can I switch between metric and US units?
Yes. Volume inputs are available in liters, milliliters, microliters, cubic meters, and US gallons.
How precise are the results?
Outputs keep up to five decimal places. For high precision work, ensure balances and volumetric glassware are calibrated.
Can it help me hit a target molarity?
Yes. Compute the required moles from target molarity × volume, or convert from mass, then confirm the molarity before preparing the solution.