Dna Concentration A260
Calculator
Results
- Concentration (µg/mL)
- 650
- Concentration (ng/µL)
- 650
- Total DNA recovered (µg)
- 65
Biology and lab results
| Concentration (µg/mL) | 650 |
| Concentration (ng/µL) | 650 |
| Total DNA recovered (µg) | 65 |
formula-map diagram
- Concentration (µg/mL)
- 650
- Concentration (ng/µL)
- 650
- Total DNA recovered (µg)
- 65
Formula breakdown
Formula
C (µg/mL) = A260 × 50 × dilution factor (dsDNA, 1 cm path)= 650
Note
Simplified model: these results use standard textbook laboratory relationships and average constants (A260 = 1 for 50 µg/mL dsDNA, 617.96 g/mol per base pair, ~110 Da per amino acid, ideal exponential growth). Real samples vary with purity, contaminants, buffer, temperature and instrument calibration. Always confirm against your own standards and protocol; do not use for diagnostic or safety-critical work.
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See all →Frequently asked questions
What does the A260 reading actually measure?+
A260 is the absorbance of ultraviolet light at 260 nanometers, the wavelength at which the purine and pyrimidine bases of nucleic acids absorb most strongly. Since absorbance is proportional to concentration (Beer-Lambert law), it is used as a proxy for how much nucleic acid is in the sample.
What is the conversion factor for double-stranded DNA?+
An A260 reading of 1.0 corresponds to approximately 50 micrograms per milliliter of double-stranded DNA, so concentration equals A260 x 50 x dilution factor. This constant differs for single-stranded DNA (about 33) and RNA (about 40), so make sure you are using the right one for your sample type.
Why do I need to account for the dilution factor and path length?+
If the sample was diluted before reading, or if the cuvette or instrument path length is not exactly 1 cm, the raw absorbance must be corrected before applying the concentration formula, otherwise the result will be off by that same factor. Most modern spectrophotometers normalize to a 1 cm path automatically, but it is worth confirming.
What does the A260/A280 ratio tell me about sample purity?+
A ratio around 1.8 indicates relatively pure double-stranded DNA, while a ratio around 2.0 is expected for pure RNA; a ratio noticeably lower than these suggests contamination with protein or phenol, which absorbs strongly near 280 nm.
Why does a low-concentration sample give an unreliable reading?+
Below roughly 2 micrograms per milliliter, absorbance readings become dominated by instrument noise and the Beer-Lambert relationship becomes less linear, so concentrations near or below this threshold should be treated as approximate, and a fluorescence-based assay is more reliable at very low concentrations.