What is the formula used?

M = (ρ × w × 10) ÷ M_r, where ρ is density in g/mL, w is mass fraction as a percentage (0–100), and M_r is molar mass in g/mol. The factor 10 converts (g/mL × %) to (g/L × fraction).

What units should I use?

Density in g/mL (same as g/cm³), mass fraction as a percentage between 0 and 100, and molar mass in g/mol. The result is in mol/L (M).

How is this different from the acid-density tool?

This tool works for any solute — salts, bases, organic solvents, polymers — not only acids. The underlying formula is identical; the presets cover a broader range of common reagents.

Where do I find density and mass fraction values?

They appear on the reagent bottle label, the Certificate of Analysis (CoA), or the Safety Data Sheet (SDS). Common values are also tabulated in CRC Handbook tables.

Can I use weight fraction (0–1) instead of percent?

No — enter the percent value (e.g. 96 for 96%). If you have the weight fraction as a decimal (e.g. 0.96), multiply it by 100 before entering.

Why does the factor 10 appear in the formula?

Density is in g/mL = g per 0.001 L. Multiplying ρ (g/mL) × w% gives g·%/mL. Dividing by 100 converts % to fraction and multiplying by 1000 mL/L yields g/L. Combined: × 10.

Density to Molarity Converter

Enter solution density, mass fraction (weight percent), and solute molar mass to instantly calculate molarity in mol/L.

Inputs

Common Reagents

Solution Density (g/mL)

Mass Fraction (weight %)

Solute Molar Mass (g/mol)

Enter values on the left and click Calculate.

Formula Reference

M = (ρ × w × 10) ÷ M_r

M — molarity (mol/L)
ρ — solution density (g/mL)
w — mass fraction (weight %)
M_r — solute molar mass (g/mol)
Factor 10 = 1000 mL/L ÷ 100 (%→fraction)

Copied!

Summary

Reagent bottles report solution density (g/mL) and mass fraction (weight percent) rather than molarity. This converter applies the standard formula — M = (density × mass fraction × 10) ÷ molar mass — to give you the molar concentration in mol/L immediately. Supply the solute's molar mass and get a full step-by-step breakdown alongside common-reagent presets.

How it works

Enter the solution density in grams per milliliter (g/mL) from the reagent label.
Enter the mass fraction (weight percent) of the solute in the solution.
Enter the molar mass of the pure solute in grams per mole (g/mol).
Click Calculate — the tool applies M = (ρ × w% × 10) ÷ M_r.
Review the step-by-step derivation showing each unit conversion.
Use the preset buttons for common reagents to auto-fill known values instantly.

Use cases

Preparing standard solutions from concentrated stock reagents in the lab.
Verifying molar concentration of commercially supplied chemicals.
Calculating volumes needed for dilution using the C1V1 = C2V2 relation.
Stoichiometric calculations for titrations and reactions.
Teaching unit conversion between density, weight percent, and molarity.
Cross-checking reagent quality certificates against expected molarity.
Formulating buffer solutions at precise molar concentrations.
Converting any solute/solvent combination — not limited to acids.

Frequently Asked Questions

Last updated: 2026-06-04 · Reviewed by Nham Vu

Density to Molarity Converter

Inputs

Result

Step-by-step Derivation

Formula Reference

Summary

How it works

Use cases

Frequently Asked Questions

Density to Molarity Converter

Use the Density to Molarity Converter

Inputs

Result

Step-by-step Derivation

Formula Reference

Summary

How it works

Use cases

Frequently Asked Questions