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.
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.”
How to use
- Choose Mass → Moles or Moles → Mass.
- Select the molecule model and enter its length, or use a supplied custom molecular weight.
- Enter the starting mass or amount.
- 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.
Related calculators
Carry the calculation in your pocket.
Save calculations and run timed protocols with RayCrest Lab Calculator on iPhone, iPad, and Apple Watch.
Connect molecular quantities to sequence workflows.
Continue mass, molarity, sequence, cloning, PCR, and NGS planning in RayCrest MDS.