DNA Copy Number Calculator

Calculate number of DNA copies, molecules, and mass from concentration and fragment size.

DNA concentration (ng/μL) (ng/μL)

Fragment/genome size (bp) (bp)

Human genome: 3.2×10⁹ bp

Volume to use (μL) (μL)

Please check your inputs and try again.

Worked Examples

Example 1: Plasmid 5000bp at 50 ng/μL, 1μL

copies = (50e-9)/(5000×650) × 6.022e23

Result: 9.3×10⁹ copies

Useful for cloning and transfection

Example 2: PCR template: human genomic DNA 50ng/μL

3.2×10⁹ bp genome

Result: copies = 23

Very few genome copies in 50 ng

Frequently Asked Questions

Why 650 g/mol per base pair?

Average molecular weight per nucleotide = 330 g/mol. Base pair (2 nucleotides) = 660 g/mol. Including the phosphate backbone, 650 g/mol per bp is the standard approximation.

For qPCR standard curves?

Create serial dilutions starting from a known copy number. Use this calculator to convert ng/μL to copies/μL to build accurate standard curves for absolute quantification.