🧬 DNA Copy Number Calculator

Molecular biology tool for DNA template preparation — qPCR / ddPCR

DNA Length — bp
Sample Vol — µL
Concentration —
Copies/µL —

DNA Template Information

Concentration & Copy Number

Reverse: Copy Number → Concentration

Dilution Calculator

Uses C₁V₁ = C₂V₂ to calculate required stock and diluent volumes.

Serial Dilution Calculator

Design a serial dilution series (e.g. 10⁸ → 10⁷ → 10⁶ → 10⁵ → 10⁴ copies/µL).

Calculation Details

Step-by-step breakdown using the values from sections ① and ②.

Formula & References

Molecular Weight (dsDNA)

MW (g/mol) = DNA length (bp) × 660 g/mol/bp

Copy Number from Concentration

Copies/µL = [DNA concentration (ng/µL) × Avogadro's number] / [DNA length (bp) × 660 × 10⁹]

Concentration from Copy Number (inverse)

Concentration (ng/µL) = [copies/µL × DNA length (bp) × 660 × 10⁹] / Avogadro's number

Dilution (C₁V₁ = C₂V₂)

Stock volume = (Target concentration × Final volume) / Stock concentration
Diluent volume = Final volume − Stock volume

Constants

ConstantValue
Avogadro's number6.022 × 10²³ molecules/mol
MW per bp (dsDNA)660 g/mol/bp

Variables & Units

VariableDescriptionUnit
DNA lengthLength of the DNA templatebp (base pairs)
DNA concentrationMass concentration of DNAng/µL or µg/µL
MWMolecular weight of the DNAg/mol
Copies/µLNumber of DNA molecules per microlitrecopies/µL
Sample volumeVolume of the DNA sampleµL
Stock concentrationConcentration of stock solutionsame unit as target
Target concentrationDesired final concentrationsame unit as stock
Final volumeDesired final volume of diluted sampleµL

Assumptions

  • All DNA types (Plasmid, Linear, PCR product, dsDNA) are treated as double-stranded DNA.
  • MW per base pair = 660 g/mol (average for dsDNA, includes sodium counter-ions).
  • Avogadro's number = 6.022 × 10²³ molecules/mol.
  • Concentration units: 1 µg/µL = 1000 ng/µL.
  • Calculation assumes pure DNA without significant contaminants.

Example (from specification)

DNA concentration = 10 ng/µL, DNA length = 5,000 bp

Molecular weight = 5,000 × 660 = 3.30 × 10⁶ g/mol

Copy Number = (10 × 6.022 × 10²³) / (5000 × 660 × 10⁹)
    = 6.022 × 10²⁴ / 3.3 × 10¹⁵
    ≈ 1.83 × 10⁹ copies/µL