Percentage Concentration to Molarity Calculator

Converting a percentage concentration to molarity is a common step in lab prep — this calculator does it for all three percent types: % w/v, % w/w, and % v/v. Select your Percent Type, then enter the Percentage, Molar Mass of your solute, and Density (required for % w/w and % v/v) to get the Molarity in mol/L. Secondary outputs show the detected concentration type and the exact formula applied.

%
g/mol

Molecular weight of the solute

g/mL

Solution density (w/w) or solute density (v/v). Not needed for w/v.

Results

Molarity

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Concentration Type

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Formula Used

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Frequently Asked Questions

What is the difference between w/w, w/v, and v/v percentage?

w/w % is grams of solute per 100 grams of solution, w/v % is grams of solute per 100 mL of solution, and v/v % is milliliters of solute per 100 mL of solution. Each requires different formulas for molarity conversion.

When do I need to enter density for the calculation?

For w/v percentages, density is not needed. For w/w percentages, you need the solution density. For v/v percentages, you need the solute density to convert volume to mass.

How is molarity calculated from percentage concentration?

The formula depends on the percentage type: w/v uses M = (% × 10) / Molar Mass, w/w uses M = (% × density × 10) / Molar Mass, and v/v uses M = (% × solute density × 10) / Molar Mass. The factor 10 converts per 100 mL to per liter.

What units should I use for molar mass and density?

Enter molar mass in g/mol and density in g/mL. The calculator will automatically handle the unit conversions to give molarity in mol/L (M).

Why is the factor 10 used in the calculation?

The factor 10 converts the concentration from 'per 100 mL' (percentage basis) to 'per liter' (molarity basis), since 1 liter = 1000 mL and 1000/100 = 10.

Can I calculate molarity for very dilute or concentrated solutions?

Yes, the calculator works for any concentration from 0.001% to 100%. However, very high concentrations may require accurate density values for precise results.

What does the significant figures option do?

When enabled, the result is rounded to a sensible number of significant figures based on the precision of your input values, following standard scientific notation practices.