Molarity Calculator
Calculate molarity using M = n/V
About the Molarity Calculator
Molarity measures solution concentration as moles of solute per liter of solution (M = n/V). The Molarity Calculator solves for molarity, moles of solute, or volume of solution when you know the other two, supporting multiple unit systems for amount (mol, mmol), volume (L, mL), and concentration (M, mM). It can also calculate mass when you provide the molar mass.
Students prepare laboratory solutions, chemists calculate reagent quantities for reactions, and pharmaceutical technicians compound medications. The calculator handles unit conversions automatically and displays results in multiple units for flexibility in lab settings.
Because calculations run entirely in your browser using JavaScript, you can solve solution concentration problems without any data leaving your device. The tool clearly distinguishes between molarity and molality in the FAQ section, a common point of confusion.
How to Use the Molarity Calculator
- Select what you want to calculate from the dropdown: molarity, moles, or volume.
- Enter the pair of values you already have, such as moles of solute and solution volume.
- Optionally enter the molar mass (g/mol) to calculate the mass of solute needed.
- Assign a unit to each field — moles or millimoles, liters or milliliters.
- Click Calculate to solve for the unknown variable and optionally the mass.
- View the results displayed in multiple units for convenience.
Why Use ToolForge’s Molarity Calculator
- Molarity computations are performed client-side in your browser—no data leaves your device, keeping your solution preparation calculations private and secure.
- Solves for any of the three variables (molarity, moles, volume) when you know the other two, and optionally calculates mass from molar mass.
- Automatically converts between moles and millimoles, liters and milliliters, matching the units commonly used in different laboratory settings.
- Shows concentration results in both M (molar) and mM (millimolar) simultaneously, covering the conventions used across chemistry disciplines.
Frequently Asked Questions
What is the molarity formula?
The molarity formula is M = n/V, where M is molarity in moles per liter (mol/L), n is the number of moles of solute, and V is the volume of solution in liters. Molarity is the most common way to express solution concentration in chemistry.
Which amount, volume, and concentration units can I work with?
The calculator supports moles and millimoles for amount of substance; liters and milliliters for volume; and molar (M) and millimolar (mM) for concentration. Mass can be calculated in grams when molar mass is provided.
Can I calculate mass from moles?
Yes, if you provide the molar mass (g/mol) of the solute, the calculator can calculate the mass needed using Mass = moles × molar mass. This is essential for preparing solutions in the laboratory.
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 is temperature-dependent because solution volume changes with temperature, while molality is not.
How do I find molar mass?
Molar mass is the mass of one mole of a substance, found by summing the atomic masses from the periodic table. For example, water (H₂O) has a molar mass of approximately 18.015 g/mol (2×1.008 + 15.999).
