DNA Concentration Calculator

Work out dna concentration instantly with clear inputs, formula shown and shareable results.

About DNA Concentration Calculator

Applies the convention that one absorbance unit at 260 nm equals 50 micrograms per millilitre of double-stranded DNA, and checks purity with the A260/A280 ratio.

Formula

Nucleic acid quantification

Concentration (microg/mL) = A260 x 50 x dilution factor for double-stranded DNA (40 for RNA, 33 for single-stranded DNA)

Worked example

With the default values below, DNA Concentration Calculator returns DNA concentration of 450.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Absorbance at 260 nmaccepts 0.001–3: 0.45
Absorbance at 280 nmaccepts 0.001–3: 0.24
Dilution factoraccepts 1–1,000: 20

Results

DNA concentration: 450.00 microg/mL
DNA concentration: 450.00 ng/microL
A260/A280 ratio: 1.8750
Purity assessment: Pure DNA (ratio 1.8 to 2.0)

Step by step

1Values used
2Nucleic acid quantification
3DNA concentration= 450.00 microg/mL
4DNA concentration= 450.00 ng/microL
5A260/A280 ratio= 1.8750
6Purity assessment= Pure DNA (ratio 1.8 to 2.0)

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is 1.8 the target ratio?

Pure DNA absorbs about 1.8 times as strongly at 260 nm as at 280 nm; protein absorbs strongly at 280 nm and lowers the ratio.

What does A260/A230 tell you?

It detects guanidine and other buffer contaminants that absorb near 230 nm.