What this is for: Converts an A260 absorbance into nucleic-acid concentration and total yield, with purity-ratio interpretation.
The formula: concentration (µg/mL) = A260 × factor (50 dsDNA / 40 RNA / 33 ssDNA) × dilution factor
How to use:
- Choose the sample type — this sets the conversion factor (dsDNA 50, RNA 40, ssDNA / oligo 33 µg/mL per A260).
- Enter the A260, A280 and A230 readings from the spectrophotometer.
- Enter the dilution factor and the sample volume (µL).
- Read the concentration (µg/mL and ng/µL), total yield (µg), and the two purity ratios with their interpretations.
DNA / RNA Concentration from A260 + Purity Ratios
Concentration = A260 × factor × dilution (dsDNA 50, ssDNA 33, RNA 40 µg/mL per OD).
Conversion factor (µg/mL per A260)
CONCENTRATION (µg/mL)
Concentration (ng/µL) — same number
Total yield (µg)
A260/A280 ratio
A260/A280 interpretation
A260/A230 ratio
A260/A230 interpretation
Prefer to work offline or keep a copy? The download link is right below.
Download the DNA/RNA Concentration from A260 workbook (.xlsx)
Download the DNA/RNA Concentration from A260 workbook (.xlsx)
Notes & limits (from the workbook): Concentration = A260 × factor × dilution (dsDNA 50, ssDNA 33, RNA 40 µg/mL per OD). Pure DNA: A260/A280 ≈ 1.8; pure RNA ≈ 2.0. A260/A230 of 2.0–2.2 suggests low salt/organic carryover.