Molarity Calculator
This molarity calculator works out the concentration of a solution in mol/L from any two of three values — molarity, solute mass, or solution volume — using the formula M = mass / (molar mass × V). It is built for chemistry students, lab technicians, and anyone who needs the math done and double-checked in seconds.
Beyond the core calculation, the tool bundles a Dilution calculator that solves the C₁V₁ = C₂V₂ equation and a Converter that translates one concentration into seven equivalent units at once. Pick a compound from the built-in library to auto-fill its molar mass, switch units freely, and read a step-by-step breakdown of every answer.
How to Use the Molarity Calculator
Choose what to solve for
In the Molarity tab, use the Solve for buttons to pick Molarity, Mass, or Volume. The target field is highlighted and filled in automatically.
Set the molar mass
Select a compound from the dropdown — such as NaCl, HCl, or glucose — to auto-fill its molar mass, or type a value manually for any other substance.
Enter the two known values
Fill in the remaining inputs and choose a unit beside each one — mol/L, mmol/L, or µmol/L for concentration; g, mg, or kg for mass; L, mL, or µL for volume.
Read the result and steps
The answer appears instantly along with the formula used and a numbered breakdown of each calculation, so you can verify the math or follow the method.
Switch to the Dilution tab to solve for C₁, V₁, C₂, or V₂ with the C₁V₁ = C₂V₂ formula, or open the Converter tab to enter one concentration plus the molar mass and see every equivalent unit at once.
Features
Three Calculation Modes
Solve for molarity, solute mass, or solution volume by entering the other two values plus the molar mass.
Common Compounds Library
Pick from 20 frequently used compounds — including NaCl, HCl, NaOH, H₂SO₄, and glucose — to auto-fill the molar mass.
Flexible Unit Support
Switch concentration between mol/L, mmol/L, and µmol/L, mass between g, mg, and kg, and volume between L, mL, and µL.
Dilution Calculator
Use C₁V₁ = C₂V₂ to solve for initial concentration, initial volume, final concentration, or final volume when preparing diluted solutions.
Concentration Unit Converter
Convert one value into seven units at once: mol/L, mmol/L, µmol/L, nmol/L, % w/v, ppm, and ppb.
Step-by-Step Results
Every answer shows the formula used and a numbered breakdown of each step, making the math easy to verify or learn.
Real-Time Calculation
Results update the moment you change a value or unit — no submit button or page reload needed.
Dark Mode Support
A clean, readable interface that adapts to a built-in dark theme for comfortable use in any lighting.
Frequently Asked Questions
What is molarity?
Molarity (M) is the concentration of a solution expressed as the number of moles of solute per liter of solution. It is one of the most common units in chemistry and is measured in mol/L.
How do you calculate molarity?
Divide the moles of solute by the volume of solution in liters: M = n / V. If you only know the mass, first convert it to moles using the molar mass, giving M = mass / (molar mass × V). The calculator does both steps for you and shows the working.
How do I find molarity from grams?
Set Solve for to Molarity, choose the compound (or enter its molar mass), then type the mass in grams and the solution volume. The tool converts grams to moles and divides by the volume to return the concentration in mol/L.
How do I find the molar mass of a compound?
Add up the atomic masses of every atom in the chemical formula. For example, NaCl = Na (22.99) + Cl (35.45) = 58.44 g/mol. You can also select a compound from the built-in dropdown to fill this value in automatically.
What is the difference between molarity and molality?
Molarity (M) is moles of solute per liter of solution, while molality (m) is moles of solute per kilogram of solvent. Molarity changes with temperature because the solution volume can expand or contract, whereas molality stays constant.
When should I use the dilution calculator?
Use it whenever you prepare a less concentrated solution from a stock solution — for example, diluting 1 M HCl to make 500 mL of 0.1 M HCl. The C₁V₁ = C₂V₂ formula tells you exactly how much stock solution to use.
What do ppm and ppb mean?
ppm (parts per million) equals mg/L for dilute aqueous solutions, and ppb (parts per billion) equals µg/L. These units are common in environmental chemistry and water-quality analysis, and the Converter tab translates between them and molar units.
Is my data stored or sent anywhere?
No. All calculations are performed entirely in your browser using JavaScript. No data is uploaded or stored on any server.
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