# Molarity Calculator

Free molarity calculator. Calculate molarity, moles, or volume using M = moles / liters. Solve for any variable with step-by-step explanations.

## What this calculates

Calculate the molarity (concentration) of a solution, the number of moles of solute, or the volume of solution needed. Uses the fundamental formula M = n / V where M is molarity in mol/L, n is moles of solute, and V is volume in liters.

## Inputs

- **Solve For** — options: Molarity (M), Moles (mol), Volume (L) — Select which variable to calculate.
- **Molarity (M)** (mol/L) — min 0 — Concentration in moles per liter.
- **Moles (mol)** (mol) — min 0 — Amount of solute in moles.
- **Volume (L)** (L) — min 0 — Volume of solution in liters.

## Outputs

- **Result** — The calculated value.
- **Unit** — formatted as text — The unit of the result.
- **Formula** — formatted as text — The formula and calculation steps.

## Details

Molarity is the most common way to express the concentration of a solution in chemistry. It is defined as the number of moles of solute dissolved per liter of solution.

The Formula: M = n / V

- M = Molarity (mol/L or M)

- n = moles of solute (mol)

- V = volume of solution (L)

Rearranged Forms

- Solve for moles: n = M × V

- Solve for volume: V = n / M

Example

If you dissolve 0.5 moles of NaCl in 2 liters of water, the molarity is:
M = 0.5 / 2 = 0.25 M (0.25 molar)

Important Notes

- Volume refers to the total volume of the solution, not just the solvent

- Molarity changes with temperature because liquid volumes expand and contract

- For temperature-independent concentration, use molality (moles per kg of solvent)

## Frequently Asked Questions

**Q: What is molarity?**

A: Molarity (M) is a measure of concentration defined as the number of moles of solute per liter of solution. A 1 M solution contains 1 mole of solute in every liter of solution. It is the most commonly used concentration unit in chemistry.

**Q: How do I find the number of moles from grams?**

A: Divide the mass in grams by the molar mass (molecular weight) of the substance. For example, 58.44 g of NaCl (molar mass = 58.44 g/mol) equals 1 mole. Use the periodic table to find atomic masses and add them up for your compound.

**Q: What is the difference between molarity and molality?**

A: Molarity (M) is moles of solute per liter of solution. Molality (m) is moles of solute per kilogram of solvent. Molality does not change with temperature because mass does not change, while molarity does because volume changes with temperature.

**Q: Can molarity be greater than 1?**

A: Yes. Concentrated solutions can have molarities well above 1 M. For example, concentrated hydrochloric acid is approximately 12 M, and concentrated sulfuric acid is approximately 18 M. The maximum molarity depends on the solubility of the solute.

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Source: https://vastcalc.com/calculators/chemistry/molarity
Category: Chemistry
Last updated: 2026-04-21