Molarity Calculator
Use this molarity calculator to find molar concentration, required solute mass, or moles in solution.
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Quick Answer: Molarity is M = n / V, with volume in liters. If you know mass, first compute moles from mass / molar mass.
What This Molarity Calculator Helps You Do
This page covers the three molarity tasks people actually use: concentration, mass needed, and moles in solution.
It keeps the mass-to-moles step visible so unit mistakes are easier to catch.
How to Calculate Molarity Calculator
- Choose the task: Solve for molarity, mass, or moles.
- Enter known values: Use grams, liters, and grams per mole consistently.
- Apply the relation: Convert mass to moles when needed, then divide or multiply by volume.
Molarity Calculator Formula
M = n / V; n = mass / molar mass; mass = M x V x molar mass
| Variable | Meaning | Unit |
|---|---|---|
| M | Molarity | mol/L |
| n | Moles of solute | mol |
| V | Solution volume | L |
Use the worked examples below to check how the formula behaves with real values. If the result looks unexpected, verify the unit assumptions and the meaning of each variable before interpreting the answer.
Worked Examples
Find molarity - 5 g NaCl in 500 mL
- Mass: 5 g
- Molar mass: 58.44 g/mol
- Volume: 500 mL
Result: Molarity is about 0.171 M.
Convert grams to moles, then divide by 0.500 L.
Find mass - 0.5 M NaOH, 250 mL
- Molarity: 0.5 M
- Volume: 250 mL
- Molar mass: 40 g/mol
Result: Required mass is 5.00 g.
Use mass = M x V x molar mass.
How to Interpret Your Results
| Range | Meaning | Action |
|---|---|---|
| Low M | Dilute solution. | Useful for routine prep and comparison. |
| High M | Concentrated solution. | Check solubility and safety assumptions. |
Frequently Asked Questions
Multiply molarity by solution volume in liters.
Because molarity is defined as moles per liter of solution.
Yes. It is the concentration measured in moles per liter.
Note: This calculator uses the standard idealized molarity relation.
References
Last reviewed: March 2026