DNA Concentration Calculator

Your details

Concentration: absorbance to µg/mL and nM. Molarity: µg/mL + length to nM. Dilution: stock + target to volume.
Selects the conversion factor (CF, in µg/mL per A260 unit at 1 cm pathlength). dsDNA uses 50, ssDNA and oligos use 33, RNA uses 40.
UV absorbance reading at 260 nm. Reliable between 0.1 and 1.0 for most spectrophotometers.
Cuvette or cell path length in centimetres. Standard cuvettes are 1 cm; NanoDrop uses 1 mm (0.1 cm).
cm
If the sample was diluted before reading, enter the dilution factor (e.g. 10 for a 1:10 dilution). Enter 1 for undiluted.
Optional - used to calculate the A260/A280 purity ratio. Leave at 0 to skip purity assessment.
Optional - used to calculate the A260/A230 purity ratio. Leave at 0 to skip.
Length in base pairs (dsDNA) or bases (ssDNA, RNA, oligo). Used to convert µg/mL to nM. Enter 0 or leave blank to skip.
Concentration (µg/mL)Pure DNA
22.5µg/mL

Mass concentration calculated from A260 using Beer-Lambert law

Concentration (ng/µL)22.5ng/µL
Molarity (nM)69.23nM
A260/A280 ratio1.88
A260/A230 ratio2.05
A260/A280 assessmentPure (acceptable)
A260/A230 assessmentPure (acceptable)
1.88 A260/A280
Low purity<1.7Pure DNA1.7-2Acceptable2-2.3High - check for RNA2.3+

Concentration: 22.500 µg/mL

  • Your dsDNA concentration is 22.500 µg/mL (22.500 ng/µL).
  • A260/A280 = 1.88: ratio is in the acceptable range (1.7-2.0), indicating low protein contamination.
  • A260/A230 = 2.05: in the acceptable range (1.8-2.2), indicating minimal carryover of chaotropic salts or organic solvents.

Next stepFor downstream applications (PCR, sequencing, NGS library prep), typical input requirements range from 1-50 ng/µL. Always dilute to the recommended input range rather than using a concentrated stock directly.

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