Protein Concentration Calculator

Find protein concentration from an A280 reading.

A280 absorbance

Path length

Extinction coeff. ((mg/mL)⁻¹cm⁻¹)

Protein concentration (mg/mL) 0.8

Formula: conc = A280 ÷ (ε × path)

Step-by-step with your numbers:

1. Values used:

2. A280 absorbance = 0.8

3. Path length = 1

4. Extinction coeff. = 1 (mg/mL)⁻¹cm⁻¹

6. Protein concentration = A280 absorbance x Path length = 0.8 x 1 = 0.8mg/mL

Did we solve your problem today?

Estimate protein concentration via UV absorbance (Beer–Lambert law).

The math behind it

conc = A280 ÷ (extinction coefficient × path length). For many proteins, 1 A280 ≈ 1 mg/mL with a 1 cm path.

A280 0.8, 1 cm, ε 1 → 0.8 mg/mL.

Exact ε?

Calculate it from the protein's amino-acid sequence for accuracy.