Percentage Concentration → Molarity Calculator

Q: Why is density needed for w/w and v/v?

Converting to molarity (moles per liter) requires density to connect mass and volume for w/w and v/v definitions.

Q: What units should density use?

g/mL. The formulas here assume density in g·mL⁻¹.

Q: Does temperature matter?

Density varies with temperature. Use a density measured at your working temperature for best accuracy.

Convert percentage concentration to molarity (M) for w/w, w/v, and v/v mixtures. Enter %, molar mass, and (when needed) density. See steps and visualize with a mini chart and a molarity gauge.

Background

For a 2-component solution, define percent as follows:

w/w % = g solute per 100 g solution → needs solution density ρ (g·mL⁻¹)
w/v % = g solute per 100 mL solution → no density needed
v/v % = mL solute per 100 mL solution → needs solute density ρ_solute (g·mL⁻¹)

Let percent be p (%), molar mass be M_m (g·mol⁻¹), and density be ρ (g·mL⁻¹). Then:

w/v: M = (p × 10) / M_m

w/w: M = (p × ρ × 10) / M_m

v/v: M = (p × ρ_solute × 10) / M_m

Here 10 converts “per 100 mL” to “per liter”.

Enter known values

Percent type:

w/v does not require density.

Strength and solute:

Enter the solute’s molar mass.

Density (if required):

For w/w: use solution density. For v/v: use solute density.

Show:

Step-by-step working

Mini chart: % / ρ / M

Molarity gauge

Round to sensible significant figures

Quick picks:

w/v doesn’t need density. w/w uses solution ρ. v/v uses solute ρ.

Result:

No results yet. Enter values and click Calculate.

How to use this calculator

Pick % type (w/w, w/v, v/v), enter % and molar mass. Provide density when prompted.
We use: w/v → M = (p × 10) / M_m; w/w → M = (p × ρ × 10) / M_m; v/v → M = (p × ρ_solute × 10) / M_m.
Toggle sig-fig rounding; view steps and visuals.