DNA Copy Number Calculator

Calculate the number of DNA or RNA molecules from mass and length. Essential for qPCR setup, cloning calculations, and molecular quantification.

Formula:
Copy Number = (Amount × Avogadro's Number) / (Length × MW per base)

Molecular Weights:
dsDNA: 660 g/mol per bp
ssDNA: 330 g/mol per nt
ssRNA: 340 g/mol per nt

What is DNA Copy Number?

DNA copy number refers to the number of molecules of a specific DNA fragment present in a sample. This calculation is crucial for qPCR template preparation, cloning efficiency, and molecular biology experiments.

How to Use This Calculator

  1. Select molecule type (dsDNA, ssDNA, or RNA)
  2. Enter the length in base pairs or nucleotides
  3. Enter the amount in your preferred unit
  4. Get instant copy number calculation

When to Use

  • qPCR template preparation
  • Cloning and transformation calculations
  • NGS library preparation
  • Viral load quantification
  • Gene therapy dosing

Key Constants

Avogadro's Number: 6.022 × 10²³

dsDNA: 660 g/mol per bp

ssDNA: 330 g/mol per nt

ssRNA: 340 g/mol per nt

Example Applications

qPCR: 10 ng of 100 bp amplicon = 9.1 × 10¹° copies

Plasmid: 1 µg of 3 kb plasmid = 3.0 × 10¹¹ copies

Genomic: 1 µg human DNA = 3.0 × 10⁵ genome copies

FAQ

Q: Why is copy number important for qPCR?
A: It determines template concentration and helps calculate efficiency and dynamic range.

Q: How many copies needed for reliable qPCR?
A: Typically 10-10⁷ copies, with optimal range of 10²-10⁵ copies per reaction.