Do I need molecular weight?

You need molecular weight to convert molar concentration to mg/mL.

What if I only need uM?

Use A280, epsilon, path length, and dilution factor; molecular weight only affects mg/mL and total mass.

Estimate protein concentration from absorbance, extinction coefficient, path length, dilution, and molecular weight.

Answer

0.8111

Protein concentration

Micromolar: 16.2222 uM

Molar concentration: 1.6222E-5 M

Total protein: 405.5556 ug

260/280 check: Low nucleic acid signal

A280A260A320 blank/scatterExtinction coefficient (M^-1 cm^-1)Path length (cm)Dilution factorMolecular weight (Da)Sample volume (mL)

mg/mL uses molar concentration multiplied by molecular weight. Use the protein's actual molecular weight when available.

Examples

Result details

Corrected A280	Path-corrected A280	A260/A280	Total protein
0.73	0.73	0.4932	405.5556 ug

c = (A280 - A320) x dilution / (epsilon x path length)

Molar concentration is converted to mg/mL by multiplying by molecular weight in daltons.

Symbol	Variable	Description
A280	Absorbance at 280 nm	Protein aromatic residue absorbance.
epsilon	Extinction coefficient	Protein-specific molar extinction coefficient.
l	Path length	Optical path length in centimeters.

1
Enter absorbance
Use A320 if you have a scatter or blank correction reading.
2
Enter protein constants
Use the protein extinction coefficient and molecular weight.
3
Read concentration
The top result shows mg/mL; molar and uM values are shown below.

A high A260/A280 ratio can suggest nucleic acid signal in a protein prep.

Ratio	Quick read
Below 0.7	Lower nucleic acid signal
0.7 or higher	Check possible nucleic acid contamination

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