About this Molarity Calculator
Molarity (M) is the standard unit for concentration in chemistry. It tells you how many moles of a solute are dissolved in one liter of solution. Use this tool to calculate molarity and total moles from mass, molar mass, and final solution volume.
Who this calculator is for
- Chemistry students preparing or checking solution concentration calculations.
- Lab users converting weighed mass into moles and final molarity.
- Anyone verifying a quick molarity setup before mixing a solution.
When to use it
- Compute molarity from a known mass, molar mass, and final solution volume.
- Check how many moles of solute are present in a prepared solution.
- Work backward from a concentration plan before preparing a lab solution.
How to use this calculator
- Enter the Mass of the solute (in grams).
- Enter the Molecular Weight (g/mol) of the substance.
- Enter the Final Volume of the solution (in Liters).
- The result is the Molarity (mol/L).
Key assumptions
- Mass, molar mass, and final solution volume are finite numeric inputs.
- Molar mass and solution volume must be greater than zero.
- The calculation assumes the entered volume is the final solution volume, not just the solvent added.
Accuracy and testing
Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.
How this calculator works
Formula:
1. Moles (n) = Mass (g) / Molecular Weight (g/mol)
2. Molarity (M) = Moles (n) / Volume (L)
Inputs explained
Mass
The amount of the chemical substance you are weighing out.
Molecular Weight
The mass of one mole of the substance (found on the periodic table or bottle label). Example: NaCl = 58.44 g/mol.
Volume
The final volume of the solution in Liters.
Understanding your results
A 1 M (1 Molar) solution contains 1 mole of solute per liter. Higher M means a more concentrated solution.
Example scenarios
Salt Solution
Mass 58.44g NaCl. MW 58.44. Vol 1L. Result: 1 Molar.
Glucose
Mass 90g. MW 180. Vol 0.5L. Moles = 0.5. Molarity = 0.5/0.5 = 1 M.
Key Features
- Mass to Moles Conversion
- Standard Chemistry Formula
- Volume Support
Tips & Best Practices
- Always convert volume to Liters before calculating (e.g., 500mL = 0.5L).
- To dilute a solution, use the formula M₁V₁ = M₂V₂.
Glossary of Terms
- Solute
- The substance being dissolved (e.g., salt).
- Solvent
- The liquid doing the dissolving (e.g., water).
- Mole
- A unit measuring the amount of substance (6.022 × 10²³ particles).