Molarity Calculator

Prepare or verify solution molarity from known moles, known solute mass plus molar mass, or a target molarity and final prepared solution volume.

How It Works

Formula

n = \frac{m}{M_w}

c = \frac{n}{V}

m = c \cdot V \cdot M_w

Variables, symbols and units

$n$: Solute amount(mol)
$m$: Solute mass(g)
$M_w$: Molar mass(g/mol)
$c$: Molarity(M)
$V$: Final prepared solution volume(L)

Calculation method explained

Pick the job that matches what you already know: moles plus final volume, mass plus molar mass plus final volume, or target molarity plus molar mass plus final volume. The page then solves only that preparation case and keeps the units explicit the whole way.

The math is normalized before solving. Solute amount is converted to mol, solute mass to g, molarity to M, and volume to L. In the mass-based concentration mode, the calculator first converts mass to moles with n = m / M_w and then converts moles to molarity with c = n / V. In the target-prep mode, it rearranges the same preparation relationship to m = c * V * M_w.

V always means the final prepared solution volume, not the solvent amount poured before the solution is brought to its final volume.

Frequently Asked Questions

What volume should I enter here?

Enter the final prepared solution volume. If you dissolve a solute and then bring the flask up to mark, the marked final volume is the correct V for this calculator.

Why does the mass-based workflow require molar mass?

Because the calculator only uses user-supplied values. It converts mass to moles with n = m / M_w, so you must provide the molar mass yourself.

How is this different from the Solution Dilution, Density, or Beer-Lambert tools?

This page is for concentration-from-amount preparation math. Solution Dilution starts from a known stock concentration, Density handles mass per volume rather than moles, and Beer-Lambert solves concentration from absorbance.

What chemistry is out of scope here?

The calculator does not model non-additive volume effects, dissociation, activity coefficients, density-based conversions, percent-solution conversions, buffer chemistry, or protocol-specific reaction behavior.

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Molarity Calculator

How It Works

Frequently Asked Questions

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