DNA Copy Number Calculator

How to use this calculator

Enter the amount of DNA in ng and its length in base pairs. The number of copies and pmol are calculated.

Formula

copies = ng × N_A ÷ (bp × 650 × 10⁹)

Example

10 ng of a 5,000 bp plasmid:

copies = 10 × 6.022 × 10²³ ÷ (5,000 × 650 × 10⁹) = 1.85e+09

Frequently asked questions

How do I convert ng of DNA to copies?

Copies = ng × 6.022 × 10²³ ÷ (length in bp × 650 × 10⁹). 650 g/mol is the average mass of one base pair.

Does it work for single-stranded DNA?

Use about 330 g/mol per nucleotide instead of 650 per base pair.

How do I make a qPCR standard curve?

Calculate copies per µL of your stock, then make 10-fold serial dilutions.

Embed this calculator