Interpreting A260/A280 ratios
A260/A280 compares nucleic acid absorbance with absorbance around 280 nm.
DNA around 1.8 and RNA around 2.0 are often considered relatively pure, but interpretation depends on method and sample context.
Calculator
A260/A280 Purity Calculator
Result
A260/A280: 1.8
This is near the common purity range for DNA or RNA, but confirm with sample context.
Practical use
Use this calculator as a planning aid for molecular biology, biochemistry, protein science, cloning, PCR, and routine bench preparation workflows.
Results should be interpreted alongside your protocol, instrument settings, reagent quality, and laboratory safety requirements.
How to cite this tool
Citation
If this calculator supports your research, you may cite it as a web-based tool.
Abdulfattah, M. A. A260/A280 Purity Calculator. Mustafa A Abdulfattah Academic Website. Available at: https://www.mustafaabdulfattah.com/tools/a260-a280-purity-calculator. Accessed today.
BibTeX
@misc{abdulfattah_a260_a280_purity_calculator_2026,
author = {Abdulfattah, Mustafa A.},
title = {A260/A280 Purity Calculator},
year = {2026},
url = {https://www.mustafaabdulfattah.com/tools/a260-a280-purity-calculator},
note = {Accessed today}
}FAQ
A260/A280 Purity Calculator questions
What is a good A260/A280 ratio for DNA?↑
DNA around 1.8 is often considered relatively pure, but this is a guideline rather than an absolute rule.
What is a good A260/A280 ratio for RNA?↑
RNA around 2.0 is often considered relatively pure, with context-dependent interpretation.
What can a low ratio suggest?↑
A lower ratio may suggest protein, phenol, or other absorbance near 280 nm.
Is this enough to confirm sample quality?↑
No. Purity ratios are screening indicators and should be interpreted with other quality checks.