Percentage Concentration to Molarity Calculator

Updated Sep 2026 Used 1 times

Use the Percentage Concentration to Molarity Calculator to calculate and interpret converted amount concentration.

Your result

Converted molarity

Enter your values, then calculate to see a verified result.

Inputs usedReview the information used for this result.

Full calculation and sourcesReview the selected percentage basis, normalized units, assumptions, and formula version.

Versioned calculationFormula v1.2.0

What is converted

A clearly labelled percentage concentration is converted to molarity using its stated basis.

Required inputs

% w/w: Percent, molar mass and density
% w/v: Percent and molar mass
% v/v: Percent, molar mass and pure-solute density

Important limitation

The v/v pathway is a nominal conversion using pure-solute density. Real mixtures can contract or expand, and density varies with temperature and purity.

Confirm w/w basisUse grams of solute per 100 g of solutionP = 37

Apply densityConvert solution mass basis to volume basisρ = 1.19 g/mL

Divide by molar massConvert grams per liter to moles per liter(10 × P × ρ) / Mr

Confirm w/v basisUse grams of solute per 100 mL of solutionP = 0.900

Convert to g/LMultiply the displayed percentage by 1010P = 9.00 g/L

Divide by molar massConvert grams per liter to moles per liter(10 × P) / Mr

Confirm v/v basisUse milliliters of liquid solute per 100 mL of stated solutionP = 70

Apply pure-solute densityConvert the stated solute volume to massρsolute = 0.789 g/mL

Divide by molar massConvert grams per liter to moles per liter(10 × P × ρsolute) / Mr

Interpretation

The converted amount concentration is .

The selected percentage basis controls whether density is used.

The result inherits uncertainty from the entered assay, density, molar mass, temperature, and composition.

Use this result

Percent Concentration vs Molarityverify the selected percentage basis.Molarity Calculatorcontinue with known solute mass and final volume.M1V1 M2V2 Dilution Formulacalculate a working dilution after obtaining stock molarity.

Percentage Concentration to Molarity Calculator: purpose and method

Calculates converted amount concentration and mass concentration used from percentage basis, percentage concentration, solute molar mass, and solution density with visible method, validation, precision, and limitations.

Keep exploring

Method and test recordFormula v1.2.0

Recorded scope: basis-specific formula, units, validation, content package, and internal-route implementation
Publisher: CalculatorGeek
Reviewed by: CalculatorGeek Editorial Team
Recorded review date: 2026-09-23
Next source review: 2027-09-23
Definition fixtures: 8 configured scenarios
Published examples: 3 shown below

Recorded method

w/w, w/v, and nominal v/v identities, basis-specific density behavior, unit-equivalent density, invalid boundaries, links, and rendered output are checked separately.

These records describe the published model and reference tests. A test-case count is not a certification of every possible input or an independent specialist review. Editorial policy

Known limitations

The percentage basis must be explicitly identified as w/w, w/v, or v/v.
Density is required for w/w and v/v: use complete-solution density for w/w and pure-solute density for v/v.
The v/v pathway is a nominal conversion that assumes the stated pure-solute volume and density; real mixtures can contract or expand, and density varies with temperature and purity.
The result does not determine chemical safety, pH, activity, solubility, or reaction stoichiometry.

Method sources

Latest model update

2026-09-23 - Added a source-bounded v/v conversion with pure-solute density, nominal-mixture limitations, independent fixtures, and a visible IUPAC volume-fraction source.

Reference inputs and expected results

These published examples are separate from the configured definition fixtures and any additional automated assertions. Expected values use the stated output units; invalid inputs are intended to be rejected.

Case	Inputs	Expected result
37% w/w	37%; density 1.19 g/mL; molar mass 36.46 g/mol	12.0762 mol/L before display rounding
0.900% w/v	0.900%; molar mass 58.44 g/mol	0.1540 mol/L before display rounding
70% v/v ethanol	70%; pure-solute density 0.789 g/mL; molar mass 46.07 g/mol	11.9883 mol/L nominal conversion before display rounding

Report an issue with this tool. Include the page URL, units, expected answer, and steps to reproduce. Do not include sensitive personal information.

On this page

Formulas used

For P percent w/w, complete-solution density rho in g/mL, and molar mass M_r in g/mol:

molarity = (10 × P × rho) / M_r

For P percent w/v and molar mass M_r in g/mol:

molarity = (10 × P) / M_r

For P percent v/v and pure-solute density rho_solute in g/mL:

nominal molarity = (10 × P × rho_solute) / M_r

Do not silently apply one basis formula to another. The v/v result is nominal because real mixture volumes can contract or expand.

Continue with Percent Concentration vs Molarity to verify the selected percentage basis.

How to use the calculator

Select % w/w, % w/v, or % v/v exactly as stated by the source label.
Enter the displayed percentage number; enter 37 for 37%, not 0.37, unless the interface explicitly requests a fraction.
Enter the molar mass of the exact solute form in g/mol.
For % w/w, enter complete-solution density. For % v/v, enter pure-solute density at the applicable temperature and purity. Density is not used for % w/v.
Calculate and review the selected formula, normalized inputs, limitations, and molarity result.

Continue with the Molarity Calculator when solute mass and final solution volume are known.

Worked example: 37% w/w

For 37% w/w, density 1.19 g/mL, and molar mass 36.46 g/mol:

molarity = (10 × 37 × 1.19) / 36.46 = 12.0762 M

The displayed result may be rounded to 12.08 M, but retain the unrounded internal value for later calculations.

Worked example: 0.9% w/v

For 0.900% w/v sodium chloride and molar mass 58.44 g/mol:

molarity = (10 × 0.900) / 58.44 = 0.1540 M

Density is not used because the w/v definition already supplies solute mass per solution volume.

Worked example: 70% v/v

For a nominal 70% v/v ethanol mixture, pure-ethanol density 0.789 g/mL, and molar mass 46.07 g/mol:

nominal molarity = (10 × 70 × 0.789) / 46.07 = 11.9883 M

This conversion treats 70 mL of pure ethanol as the stated component volume per 100 mL of final mixture. Actual mixture behavior depends on temperature, purity, and volume contraction, so use measured product data when exact laboratory preparation matters.

Required input behavior

Percentage must be greater than zero and no greater than 100.
Molar mass must be greater than zero.
Density must be required for w/w and v/v, and hidden or ignored for w/v.
The result changes linearly with percentage and, for w/w or v/v, with the applicable density.
Changing percentage basis changes the displayed equation, density guidance, and required inputs.
The page rejects an unspecified basis and nonpositive required values.
The v/v result must remain labelled as a nominal conversion with temperature, purity, and mixture-volume limitations.

Limitations

The result inherits uncertainty from percentage assay, density, molar mass, temperature, purity, and product composition. For v/v, the calculation converts stated pure-solute volume using pure-solute density; real mixtures can contract or expand, so the result is nominal rather than a substitute for a measured final concentration. The calculator does not determine chemical safety, mixing order, activity, pH, solubility, or reaction stoichiometry. Use batch-specific documentation where exact preparation matters.

Inputs, outputs and result meaning

Converts % w/w, % w/v, or % v/v concentration into amount concentration and the mass concentration used, with basis-specific inputs, formula disclosure, validation, precision, and limitations.

Inputs

Percentage basis: Choose the basis exactly as stated by the source: percent by mass (% w/w), percent mass per volume (% w/v), or percent volume per volume (% v/v).
Percentage concentration: Enter 37 for 37%, not 0.37. Supported units include percent (%). The supported range is 0.000000001 through 100.
Solute molar mass: Enter the molar mass of the exact solute form. Supported units include grams per mole (g/mol). The supported range is 0.000000001 through 10,000,000.
Density required by basis: For w/w, use complete-solution density. For v/v, use pure-solute density at the applicable temperature and purity. Density is not used for w/v. Supported units include grams per milliliter (g/mL) and kilograms per liter (kg/L).

Outputs

Converted amount concentration: This is the primary result in mol/L and uses up to four decimal places.
Mass concentration used: This is the basis-normalized solute mass in g/L and uses up to three decimal places.

The active formula is shown with the result. Keep the result label, unit, selected basis, density meaning, and stated limitations together when sharing the answer.

Frequently asked questions

Why does w/w require density?

Mass percent is based on solution mass, while molarity is based on solution volume. Complete-solution density converts between those bases.

Why does w/v not require density?

The w/v definition already supplies solute mass per solution volume.

Can I use this for v/v percentage?

Yes. Select % v/v and enter the pure-solute density at the relevant temperature and purity. The result is nominal because real mixture volumes can contract or expand.

Which density should I enter?

For w/w, enter density of the complete solution. For v/v, enter density of the pure solute. Do not substitute solvent density, and use condition-specific source data where precision matters.