🧬 DNA Copy Number Calculator
Convert a mass of double-stranded DNA into the number of molecules (copies), based on fragment length.
What This Calculator Does
This calculator converts a mass of double-stranded DNA into the number of individual DNA molecules (copies) present, which is essential for setting up qPCR standard curves and copy-number based assays.
The Formula
It uses the standard equation: Copy number = (Mass in ng × 6.022×1023) / (Fragment length in bp × 1×109 × 650). This assumes an average molecular weight of 650 g/mol per base pair of double-stranded DNA, and uses Avogadro’s number to convert moles of DNA into a molecule count.
- Fragment length should be the total size of your DNA molecule (e.g., plasmid or amplicon) in base pairs.
- Copies per µL is calculated by dividing the total copy number by your reaction or stock volume.
This calculation is a standard approximation used widely in molecular biology for general planning and educational purposes; actual DNA molecular weight can vary slightly with base composition.