CalculatorCast
Math Finance Health & Fitness Date & Time Unit Converters Computer Physics Chemistry Construction Engineering Statistics Education Everyday Life Biology Automotive Cooking & Food Sports & Fitness Real Estate Photography Electrical Agriculture Travel Business
All Calculators Favorites ()
English Español Français Deutsch Português Italiano Nederlands Polski Türkçe 日本語 한국어 Svenska Norsk Dansk Suomi עברית

Copy Number Calculator

DNA molecule count from mass and fragment length.

Introduction

Copy Number Calculator — DNA molecule count from mass and fragment length. Enter DNA mass (ng), Fragment length (bp) to get an instant, accurate result.

Formula

Molecule count = (mass in ng × Avogadro's number 6.022×10²³) / (length in bp × 650 g/mol/bp × 10⁹) — converts a mass of dsDNA into an absolute number of DNA molecules (copies), using the ~650 g/mol/bp approximation for molecular weight.

Step-by-step

  1. Enter the DNA mass (ng).
  2. Enter the Fragment length (bp).
  3. Click Calculate to see your result instantly.

Real-world example

Example: With DNA mass (ng) = 100, Fragment length (bp) = 3000, the Copy Number Calculator gives Molecules: 30882051282.0513.

Frequently Asked Questions

Why is Avogadro's number used here?
Avogadro's number (6.022×10²³ molecules per mole) is the conversion factor between moles of DNA and an actual molecule count, once the mass has been converted to moles using the molecular weight.
What is this typically used for?
Commonly for qPCR standard curve preparation or NGS library quantification, where you need to know the exact number of DNA copies (not just the mass) in a known-concentration sample.
What inputs does the Copy Number Calculator need?
You'll need to provide: DNA mass (ng), Fragment length (bp). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Copy Number Calculator?
The Copy Number Calculator applies the formula exactly as calculated — Molecule count = (mass in ng × Avogadro's number 6.022×10²³) / (length in bp × 650 g/mol/bp × 10⁹) — converts a mass of dsDNA into an absolute number of DNA molecules (copies), using the ~650 g/mol/bp approximation for molecular weight. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Copy Number Calculator free to use?
Yes, the Copy Number Calculator is completely free, requires no signup, and runs instantly in your browser.

About the Copy Number Calculator

The Copy Number Calculator uses a real, verifiable formula — Molecule count = (mass in ng × Avogadro's number 6.022×10²³) / (length in bp × 650 g/mol/bp × 10⁹) — converts a mass of dsDNA into an absolute number of DNA molecules (copies), using the ~650 g/mol/bp approximation for molecular weight. — so results are accurate every time, not an approximation.