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DNA & Primer Calculator

Copy number from ng and length, primer reconstitution (nmol → µL), and µg ↔ pmol for dsDNA. The same math as the Excel workbook, live in your browser.

What this is for: DNA copy number from length and mass, primer reconstitution volumes, and dsDNA mass ↔ moles conversions.

The formula: copies = mass (g) × 6.022e23 ÷ (length (bp) × 660 g/mol)

How to use:

  1. In section A, enter the DNA length (bp) and amount (ng) to get the copy number.
  2. In section B, enter the primer amount (nmol) from the tube label and the desired stock concentration (µM) to get the µL of buffer or water to add.
  3. In section C, enter the DNA length (bp) and mass (µg) to get pmol, or enter an amount (pmol) to get the reverse mass (µg).
  4. Read each result in its section — results update as you type.

A. Copy Number

Uses 660 g/mol per bp for dsDNA and Avogadro's number 6.022e23.

Copies

B. Primer Reconstitution

Buffer / water to add (µL)

C. dsDNA Mass ↔ Moles

Amount (pmol)
Reverse: mass (µg)
Prefer to work offline or keep a copy? The download link is right below.
Download the DNA & Primer Calculator workbook (.xlsx)
Notes & limits (from the workbook): Uses 660 g/mol per bp for dsDNA and Avogadro's number 6.022e23. Copy number: amount (ng) × 6.022e23 / (length (bp) × 660 × 1e9). Primer reconstitution: nmol × 1000 / desired µM gives µL to add.