What Is Molarity?

Molarity (M) is a measure of the concentration of a solution, defined as the number of moles of solute per liter of solution. It is one of the most widely used units in chemistry for expressing concentration.

Core Formula: M = n / V = mass / (molar mass × V)

Formula Variables

M — Molarity

Measured in mol/L (moles per liter)

n — Moles of Solute

Amount of substance in moles (mol)

V — Solution Volume

Total volume in liters (L)

mass — Solute Mass

Weight of solute in grams (g)

Molar Mass

Molecular weight in g/mol

About This Calculator

This comprehensive tool helps you quickly calculate molarity, solute mass, or solution volume when you know two of the three values. It also includes a dilution calculator using the C₁V₁ = C₂V₂ formula and a concentration unit converter for switching between mol/L, ppm, % w/v, and other common units.

Molarity Calculations

Calculate concentration, mass, or volume with automatic unit conversion

Solve for any variable
Multiple unit options
Step-by-step solutions

Dilution Calculator

Prepare diluted solutions using the C₁V₁ = C₂V₂ equation

Stock solution prep
Four-variable solver
Instant results

Unit Converter

Convert between seven concentration units simultaneously

mol/L, mmol/L, µmol/L
% w/v, ppm, ppb
Real-time conversion

How to Use

Molarity Calculator

Select Target Variable

Choose what you want to solve for: Molarity, Mass, or Volume.

Choose Compound

Select a compound from the dropdown (e.g., NaCl, HCl) to auto-fill the molar mass, or enter it manually.

Enter Known Values

Input the two known values with their units (supports g, mg, kg for mass; L, mL, µL for volume).

View Results

The result appears instantly with a step-by-step breakdown of the calculation.

Dilution Calculator

Select Unknown Variable

Choose which variable to solve for: C₁ (initial concentration), V₁ (initial volume), C₂ (final concentration), or V₂ (final volume).

Input Known Values

Enter the three known values with appropriate units.

Calculate Result

The calculator applies C₁V₁ = C₂V₂ and shows the result with detailed steps.

Unit Converter

Enter Value

Input a concentration value and select its unit

Add Molar Mass

Enter the molar mass of the compound

View Conversions

All equivalent concentrations display instantly

Features

Three Calculation Modes

Solve for any unknown variable — molarity, solute mass, or solution volume — by providing the other two values along with the molar mass of the compound.

Common Compounds Library

Quickly select from 20 frequently used compounds including NaCl, HCl, NaOH, H₂SO₄, glucose, and more. The molar mass is automatically filled in when you select a compound.

Flexible Unit Support

Concentration: mol/L, mmol/L, µmol/L
Mass: g, mg, kg
Volume: L, mL, µL

Dilution Calculator

Use the C₁V₁ = C₂V₂ equation to calculate any one of the four variables (initial concentration, initial volume, final concentration, or final volume) when preparing diluted solutions.

Concentration Unit Converter

Convert between seven concentration units simultaneously: Molarity (mol/L), Millimolar (mmol/L), Micromolar (µmol/L), Nanomolar (nmol/L), % w/v, ppm, and ppb.

Step-by-Step Results

Every calculation shows the formula used and a numbered breakdown of each step, making it easy to verify the math or learn the process.

Privacy First: All calculations are performed entirely in your browser using JavaScript. No data is uploaded or stored on any server.

Frequently Asked Questions

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 (M)

Temperature Dependent

Moles per liter of solution
Changes with temperature
Volume can expand/contract
Most common in lab work

Molality (m)

Temperature Independent

Moles per kilogram of solvent
Remains constant
Mass doesn't change
Used in colligative properties

How do I find the molar mass of a compound?

Add up the atomic masses of all atoms in the chemical formula. You can also select a compound from the built-in dropdown to auto-fill this value.

Example: NaCl = Na (22.99) + Cl (35.45) = 58.44 g/mol

Quick Reference for Common Compounds:

Compound	Formula	Molar Mass (g/mol)
Sodium Chloride	`NaCl`	58.44
Hydrochloric Acid	`HCl`	36.46
Sodium Hydroxide	`NaOH`	40.00
Sulfuric Acid	`H₂SO₄`	98.08
Glucose	`C₆H₁₂O₆`	180.16

When should I use the dilution calculator?

Use it whenever you need to prepare a less concentrated solution from a stock solution. The formula C₁V₁ = C₂V₂ tells you exactly how much stock solution to use.

Practical Example: Diluting a 1 M HCl stock to make 500 mL of 0.1 M HCl

Common Use Cases:

Preparing working solutions from concentrated stock
Serial dilutions for calibration curves
Adjusting reagent concentrations for experiments
Creating standard solutions for titrations
Diluting samples for analysis within instrument range

What do ppm and ppb mean?

ppm (parts per million) equals mg/L for dilute aqueous solutions. ppb (parts per billion) equals µg/L. These units are commonly used in environmental chemistry and water quality analysis.