ng/mL To Molarity Calculator

Convert ng/mL and other mass concentrations to M, mM, µM, nM, or pM using molecular weight, or solve for mass concentration or molecular weight.

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Calculator Functions

Function	What it does	What it requires
Molarity (ng/mL → µM, nM)	Converts a mass concentration to a molar concentration in M, mM, µM, nM or pM	Requires the mass concentration and the molar mass of the solute
Mass concentration (µM → ng/mL)	Converts a molar concentration to a mass concentration in pg/mL, ng/mL, µg/mL, mg/mL or g/L	Requires the molarity and the molar mass of the solute
Molar mass	Finds the molar mass that links a mass concentration to a molar concentration	Requires the mass concentration and the molarity of the same solution

Mass concentration can be entered in pg/mL, ng/mL, µg/mL, mg/mL or g/L, molarity in M, mM, µM, nM or pM, and molar mass in g/mol, Da or kDa. Each result is also listed in every other unit of its kind. No sample volume is needed, because both concentrations are already per unit volume.

ng/mL to Molarity Formulas

Molar concentration is the amount of solute in moles divided by the volume of the solution, mass concentration is the mass of solute divided by that volume [1], and molar mass is mass divided by amount [1]. Dividing a mass concentration in g/L by the molar mass in g/mol therefore gives mol/L. One ng/mL is 10⁻⁶ g/L, which is where the factor of 10⁶ comes from.

Molarity (ng/mL → µM, nM)

For a result in µM, the mass concentration in ng/mL is divided by MW alone. A solution of 50 ng/mL of a compound with a molar mass of 100 g/mol is 50 ÷ (100 × 10⁶) = 5 × 10⁻⁷ mol/L, which is 0.5 µM or 500 nM. For 10 ng/mL at 300 g/mol the result is 33.33 nM, and for 100 ng/mL of a 150 kDa protein it is 0.667 nM.

Mass concentration (µM → ng/mL)

C is in ng/mL. A 1 µM solution of a 300 g/mol compound is 1 × 300 = 300 ng/mL, and 1 µM of a 50 kDa protein is 50,000 ng/mL, or 50 µg/mL. Starting from nM, the result is divided by 1,000: 1 nM of the 300 g/mol compound is 0.3 ng/mL.

Molar mass

C is in ng/mL and c in mol/L. A solution that is both 50 ng/mL and 0.5 µM has a molar mass of 50 ÷ (5 × 10⁻⁷ × 10⁶) = 100 g/mol. Both concentrations must be greater than zero.

ng/mL to nM Conversion Table

The conversion depends on the molar mass, so there is no single factor. For each molar mass, the table gives 1 ng/mL in nM and 1 µM in ng/mL.

Molar mass	1 ng/mL equals	1 µM equals
100 g/mol	10 nM	100 ng/mL
200 g/mol	5 nM	200 ng/mL
300 g/mol	3.333 nM	300 ng/mL
500 g/mol	2 nM	500 ng/mL
1,000 g/mol (1 kDa)	1 nM	1,000 ng/mL
10 kDa	0.1 nM	10,000 ng/mL
50 kDa	0.02 nM	50,000 ng/mL
150 kDa	0.006667 nM	150,000 ng/mL

Limits of This Estimate

• The molar mass must be that of the exact form in the solution. A salt, a hydrate or an oligomer has a different molar mass from the free compound, and the result changes in proportion.
• A molecular mass in daltons is treated as the same number in g/mol. The dalton is another name for the unified atomic mass unit [2], and for laboratory work the two numbers agree.
• The result is a unit conversion. It makes no adjustment for purity, biological activity, dissociation or how an assay responds.
• M and “molarity” are still common on reagent labels, but the SI guide treats them as obsolete and writes the unit as mol/L [1].

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