Percent to molarity calculator
Enter the percent and density from the bottle label and the formula to get the molar concentration before you dilute.
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How to use it
- Enter substance formula, mass percent and solution density.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Molarity = (percent ÷ 100) × density (g/mL) × 1000 ÷ molar mass; concentration (g/L) = (percent ÷ 100) × density × 1000.
Example
Inputs: Substance formula = HCl, Mass percent = 37 % w/w, Solution density = 1.19 g/mL. Result: Molarity: 12.0769 mol/L; Solute per liter: 440.3 g/L; Molar mass: 36.458 g/mol.
Limits and caveats
- Take percent and density from the label or certificate of analysis; they vary slightly by batch and with temperature.
- When diluting concentrated acid, add the acid slowly to water, never the reverse.
Questions about this tool
What is the molarity of 37% hydrochloric acid?
With a density of 1.19 g/mL it is about 12.08 mol/L.
What is the molarity of 98% sulfuric acid?
At 1.84 g/mL it is about 18.39 mol/L; it is diprotic, so its acid equivalents are higher.
How do I dilute once I know the molarity?
Use C1V1 = C2V2 to find the volume of concentrate needed for your target volume and concentration.