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DNA & RNA

Nucleic Acid Mass ↔ Moles Calculator

Convert DNA or RNA mass to moles and molecules—or moles back to mass. Add a sample volume to calculate molarity.

Calculations run locally in your browser. Values are only placed in a URL when you choose “Copy Shareable Link.”

Molecule and amount

Calculation direction

Worked example

For 1 µg of a 1,000 bp dsDNA fragment, the approximate molecular weight is 660 kDa. The sample contains about 1.52 pmol, or 9.12 × 1011 molecules. In 20 µL, that is about 75.8 nM.

How to use

  1. Choose Mass → Moles or Moles → Mass.
  2. Select the molecule model and enter its length, or use a supplied custom molecular weight.
  3. Enter the starting mass or amount.
  4. Optionally enter sample volume for molarity, then review and copy the bench-ready record.

Assumptions

dsDNA uses 660 g/mol per bp. Unmodified ssDNA uses length × 307.97 + 18.02 g/mol. The ssRNA mode explicitly estimates an unmodified transcript with a 5′ triphosphate using length × 320.5 + 159 g/mol. Avogadro’s constant is exactly 6.02214076 × 1023 mol−1.

Validation and limitations

Length-based molecular weights are approximations. Modified, labeled, capped, polyadenylated, or differently terminated molecules should use a supplier-provided or sequence-specific custom molecular weight. The result does not assess purity, integrity, amplifiability, or biological activity and does not replace a validated laboratory SOP.

Calculation record

Methodology and scientific authority

Convert nucleic-acid mass and molar amount in either direction, with optional molecule count and molarity.

Engine
nucleic-acid-mass-moles 1.0.0
Content updated

Methodology

Uses mass = moles × molecular weight, the selected molecular-weight model, and the exact Avogadro constant; optional volume adds molarity.

Inputs

  • direction
  • molecule type
  • length or custom molecular weight
  • mass or molar amount
  • optional sample volume

Outputs

  • mass
  • moles
  • molecules
  • molarity when volume is supplied

Validation examples

These scientific fixtures are reproducible tests of the calculation engine, not build-only checks.

  • 1 µg of 1,000 bp dsDNA yields about 1.515 pmol and 9.124 × 10^11 molecules. Test: one-ug-one-kb
  • Molecular weights agree with the Copy Number engine. Test: shared-mw-source

Assumptions and limitations

Assumptions

  • Length-based molecular weights are averages and use the same shared source as Copy Number.
  • Custom molecular weight is required for modified or supplier-characterized material.

Limitations

  • The model does not capture sequence composition, end chemistry, caps, labels, counterions, damage, purity, integrity, or biological function.

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