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Protein converterkDa concentration calculator

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Protein µM to mg/mL and mg/mL to µM Converter

Convert protein concentration between micromolar, mg/mL, andµg/mL using molecular weight in kDa. This is useful when connecting molar concentration to mass concentration for assays, stocks, and sample preparation.

Calculator

Convert protein concentration units

Direction of conversion

How the conversion works

Enter the protein concentration and molecular weight, then choose the direction of conversion. The calculator converts between molar concentration and mass concentration for purified proteins.

µM means micromolar concentration, or micromoles of protein per liter. It describes how many protein molecules are present in solution, which is often useful for enzyme kinetics, binding studies, stoichiometry, and molar assay design.

mg/mL means milligrams of protein per milliliter, while µg/mL describes micrograms per milliliter. These mass concentrations are common in stock preparation, purification records, loading samples, and assay reporting.

Molecular weight is needed because different proteins have different masses per molecule. A 10 µM solution of a 20 kDa protein contains less mass per volume than a 10 µM solution of a 100 kDa protein.

Practical use

Multiply concentration in µM by molecular weight in kDa, then divide by 1000. For example, 10 µM of a 50 kDa protein is 0.5 mg/mL.

The same relationship can be used in reverse when a protocol gives mg/mL or µg/mL and you need molar concentration for binding, enzyme activity, stoichiometry, or dilution planning.

This conversion is especially useful when comparing A280, Bradford, BCA, and stock solution records, because each workflow may report protein concentration in a different unit.

How to cite this tool

Citation

If this calculator supports your research, you may cite it as a web-based tool.

Abdulfattah, M. A. Protein µM to mg/mL Converter. Mustafa A Abdulfattah Academic Website. Available at: https://www.mustafaabdulfattah.com/tools/protein-um-to-mgml-converter. Accessed today.

BibTeX
@misc{abdulfattah_um_mgml_converter_2026,
author = {Abdulfattah, Mustafa A.},
title = {Protein µM to mg/mL Converter},
year = {2026},
url = {https://www.mustafaabdulfattah.com/tools/protein-um-to-mgml-converter},
note = {Accessed today}
}

FAQ

Protein concentration conversion questions

How do I convert µM protein to mg/mL?↑

Multiply concentration in µM by molecular weight in kDa, then divide by 1000. For example, 10 µM of a 50 kDa protein is 0.5 mg/mL.

Why do I need molecular weight for this conversion?↑

Molar concentration counts molecules, while mg/mL describes mass per volume. Molecular weight connects molecule count to mass, so the conversion depends on the protein size.

How do I convert mg/mL back to µM?↑

Use the reverse relationship with the molecular weight in kDa. For example, 0.5 mg/mL of a 50 kDa protein is 10 µM.

What is the formula for µM to mg/mL?↑

The conversion uses the protein concentration in µM and the molecular weight in kDa to calculate mass concentration. The calculator handles the unit conversion directly.

Is kDa the same as g/mol for this calculation?↑

For this conversion, 1 kDa corresponds numerically to 1000 g/mol. That relationship is why the simplified conversion works directly with concentration in micromolar and molecular weight in kDa.

Why is this useful for protein assays?↑

Many biochemical workflows compare molar concentration, mass concentration, and assay loading amounts. This conversion helps connect binding, enzyme, stock, and protein assay conditions.