A260 Absorbance to Concentration Calculator
Convert UV absorbance at 260 nm (A260) to concentration for dsDNA, ssDNA, or RNA. Tailored for cuvette spectrophotometer measurements with adjustable dilution factors and path lengths.
Measurement Inputs
Input absorbance, nucleic acid type, and dilutions.
Nucleic Acid Concentration
* Equal to 25.0 ng/μL.
Expert Tip
Ensure your A260 reading falls within the spectrophotometer's linear range (typically 0.1 to 1.0 OD). If the reading is too high, dilute the sample and adjust the dilution factor parameter accordingly.
Methodology & Equations
Beer-Lambert Law Application
Absorbance spectroscopy relates light extinction to substance concentration:
Standard Conversion Constants
At 260 nm wavelength, an optical density (OD) of 1.0 corresponds to standard mass concentrations:
- dsDNA: 50 μg/mL (or ng/μL)
- ssDNA: 33 μg/mL (or ng/μL)
- RNA: 40 μg/mL (or ng/μL)
How to Convert A260 Absorbance to Concentration
Quantify nucleic acids using UV-spectrophotometry at 260 nm:
Record A260 Value
Measure the absorbance of your sample at 260 nm.
Select standard constants
Factor = 50 µg/mL for double-stranded DNA, 33 µg/mL for single-stranded DNA, or 40 µg/mL for RNA.
Calculate Concentration
Multiply absorbance by the nucleic acid constant and your dilution factor: Concentration = A260 × Constant × Dilution Factor.
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