A free online molecular biology calculator to help calculate the concentration of a nucleic acid solution (either DNA, RNA or oligonucleotides) from the optical density absorbance value measured by a spectrophotometer (using a wavelength of 260 nm).

Instructions for DNA Quantification
Follow the manufacturers guidelines for operating your specific spectrophotometer
Dilute your sample as necessary in either water or TE buffer. TE buffer is best, to maintain a neutral pH
Generally, blank the spectrophotometer using whatever buffer your sample is dissolved in
Measure optical density of DNA or RNA sample, enter absorbance value OD260 in the form below
Enter dilution factor. For example if you diluted 2µl of sample in 100µl of dH2O, the dilution factor would be 50
Enter volume of stock nucleic acid sample. for example if you had 1ml of DNA solution, enter 1000 (microliter)
Click on Calculate
The results show total amount of nucleic acid in the sample along with the concentration per microlitre

Please choose how many DNA sample you have:
one two three

Please enter follow information:
Sample Name:     Absorbance (OD):       Dilution         Stock Volume (uL)