Dna Copy Number Calculator

ng/µL
bp
Length of the DNA fragment in base pairs.
Biology

Calculate the number of DNA copies per microliter from a known concentration and fragment length.

Formula

Copies/µL = (6.022×10²³ × conc ng/µL × 10⁻⁹) ÷ (bp × 660 g/mol/bp)
  • Avogadro's number = 6.022 × 10²³ molecules/mol.
  • Average molecular weight of a base pair = 660 g/mol.
  • Concentration is converted from ng to g (×10⁻⁹).

10 ng/µL, 500 bp fragment

Inputs
  • DNA Concentration: 10 ng/µL
  • Fragment Length: 500 bp

Copies = (6.022×10²³ × 10 × 10⁻⁹) / (500 × 660) ≈ 1.82×10¹⁰ copies/µL.

Frequently asked questions

What units should I use?
Concentration in ng/µL, fragment length in base pairs (bp).
Is this for single or double-stranded DNA?
This formula applies to double-stranded DNA. For ssDNA use 330 g/mol/nt instead of 660.