Molarity Calculator - Calculate Solution Concentration (M = n/V) | Free Online Tool

A molarity calculator (also called a solution concentration calculator or M = n/V calculator) is an online tool that computes the molarity of a solution using the fundamental chemistry equation M = n / V, where M is molarity (mol·L⁻¹), n is the number of moles of solute, and V is the volume of the solution in liters. Molarity is the most common unit for expressing solution concentration, used in virtually every chemistry lab and industry that deals with aqueous solutions. A 1.00 molar solution (1.00 M) contains 1.00 mol of solute in every 1.0 L of solution.

Students in high school and college chemistry use molarity calculations daily for:

• Preparing standard solutions for titration and calibration
• Stoichiometry calculations involving aqueous reactions
• Dilution problems (M₁V₁ = M₂V₂)
• Concentration conversions (percentage to molarity, etc.)

Researchers, lab technicians, and industrial chemists use molarity to:

• Accurately prepare reagents for chemical reactions
• Calculate the mass of compound needed for a desired solution concentration
• Scale chemical reactions from lab‑scale to production‑scale
• Control solution properties in pharmaceutical, food, and environmental testing

This free online molarity tool operates entirely within your browser - no data is sent to any server, ensuring your privacy and enabling offline use. It supports 5 volume units (L, mL, μL, cm³, dm³) and 5 concentration units (M, mM, μM, nM, pM), with automatic unit conversion. You can also use the calculator to solve for moles (n = M × V) or volume (V = n / M), making it a complete solution for all three rearranged forms of the molarity equation. Whether you're a student verifying a homework problem, a lab technician preparing a precise solution, or a researcher calculating stock concentrations, this calculator is your go‑to tool.

Using this solution concentration calculator is straightforward. Just follow these steps:

1. Choose what you want to calculate by selecting from the “Calculate” dropdown. Options include:
   • Molarity: Solve M = n / V (given moles and volume)
   • Moles: Solve n = M × V (given molarity and volume)
   • Volume: Solve V = n / M (given moles and molarity)
2. Enter the known values for the required fields. For example, in "Molarity" mode, enter the number of moles and the solution volume. In "Volume" mode, enter the moles and the molarity.
3. Select the appropriate units from the dropdown menus. Volume units include liters (L), milliliters (mL), microliters (μL), cubic centimeters (cm³), and cubic decimeters (dm³). Concentration units include Molar (M), Millimolar (mM), Micromolar (μM), Nanomolar (nM), and Picomolar (pM).
4. View the result. The calculation happens automatically as you type (no need to press a separate Convert button). The result appears in the output panel, and you can copy it to your clipboard with a single click.
5. Use Clear All to reset all values and start a new calculation.

The calculator also supports very small and very large numbers, making it useful for everything from concentrated stocks to trace analysis.

Tip: To calculate moles from mass (when you know the grams of solute but not the moles), use the formula n = m / MW, where m is mass in grams and MW is molecular weight in g·mol⁻¹. Then enter the resulting moles into the calculator.

Molarity (M) is defined as the number of moles of solute dissolved in exactly one liter of solution. It is one of the most commonly used concentration units because it directly relates the amount of substance (in moles) to the volume of the solution, making stoichiometric calculations straightforward.

The formula can be rearranged to solve for any of the three variables:

• Molarity: M = n / V
• Moles: n = M × V
• Volume: V = n / M

The SI unit for molarity is mol·L⁻¹, often written as M (molar). A 1 M solution contains 1 mole of solute per liter of solution. Because molarity depends on volume, it is temperature‑dependent - volume expands with temperature, so the concentration changes slightly with temperature. (This is one difference between molarity and molality; the latter is based on mass of solvent and is temperature‑independent.)

Because molality uses the mass of the solvent rather than the volume of the solution, it is independent of temperature. This makes molality the correct unit for colligative properties such as boiling point elevation and freezing point depression. However, for most everyday laboratory work and stoichiometric calculations, molarity is more convenient and widely used.

• Completely free, no registration. Unlimited calculations with no hidden costs.
• Privacy‑first design. All calculations happen locally in your browser. Your data never leaves your device.
• Solves for any variable - molarity, moles, or volume. Simply select your calculation mode.
• Supports 5 volume units and 5 concentration units - from picoliters to liters, from picomolar to molar.
• High precision with results to 6 decimal places, suitable for educational, lab, and research use.
• Works offline after initial page load.
• Fully responsive design with resizable panels on desktop for custom workflow.