DNA Copy Number Calculator

DNA copy number is calculated by first determining the molecular weight from the DNA length (bp × 660 g/mol for dsDNA or bp × 330 g/mol for ssDNA), then converting mass to moles, and finally using Avogadro's number (6.022×10²³) to calculate the number of molecules.

Double-stranded DNA (dsDNA) has approximately 660 g/mol per base pair, while single-stranded DNA (ssDNA) has about 330 g/mol per base. This difference affects the molecular weight calculation and ultimately the copy number result.

DNA length in base pairs is essential for calculating the molecular weight of your specific DNA fragment. The molecular weight is directly proportional to the length and is needed to convert mass (ng) to moles, then to copy number.

Yes, you can select single-stranded RNA which uses approximately 340 g/mol per base. RNA calculations follow the same principles as DNA but with different molecular weight constants.

Use custom molecular weight when you know the exact molar mass of your DNA fragment, especially for modified oligonucleotides, DNA with unusual base compositions, or when maximum accuracy is required for quantitative applications.

The default values (660 g/mol per bp for dsDNA, 330 g/mol for ssDNA) are widely accepted approximations that work well for most applications. For research requiring high precision, consider using experimentally determined molecular weights.

The calculator uses ng/µL for concentration, base pairs (bp) for length, and µL for volume. Results are given in copies/µL and total copies. All calculations use standard molecular biology units.

First calculate your stock solution's copy number, then determine the dilution needed to achieve your desired template concentration (typically 10³ to 10⁶ copies per reaction). Use the total copies output to plan your dilution series.