DNA & RNA Molarity Calculator (ng ↔ pmol)
Convert between mass, moles, molarity and copy number for DNA/RNA.
Convert nucleic-acid quantities the way you need them in the lab: ng to pmol, molar mass, molarity in nM or µM, ng/µL and copy number. Enter a length for dsDNA, ssDNA or RNA — or paste a sequence for an exact molar mass from base composition. Handy for ligation ratios, qPCR standards, library prep and normalizing samples.
Without a sequence, molar mass uses average per-unit masses (≈650 g/mol per bp for dsDNA, 330 per nt for ssDNA, 340 per nt for ssRNA). Paste a sequence for an exact value from base composition.
Design, edit, and verify complete constructsSeqStudio combines sequence editing and annotation, plasmid maps, primer/cloning/CRISPR design, Sanger verification, and GenBank/SnapGene files in one workspace.
How to use the DNA Molarity / ng↔pmol tool
- 1Choose the molecule type and enter the length in bp or nt (or paste a sequence).
- 2Enter the mass in nanograms and, optionally, the volume in microlitres.
- 3Read the amount in pmol, the molar concentration and the copy number.
Frequently asked questions
How do I convert ng to pmol of DNA?
pmol = ng × 1000 / molar mass (g/mol). The molar mass comes from the length and molecule type, or exactly from a pasted sequence. Enter your mass and the tool does the conversion both ways.
What average molar masses are used?
Without a sequence we use ≈650 g/mol per base pair for dsDNA, 330 g/mol per nucleotide for ssDNA and 340 g/mol per nucleotide for ssRNA. Paste a sequence for an exact value from base composition.
How is copy number calculated?
Copies = moles × Avogadro's number (6.022 × 10²³). It is useful for making qPCR standard curves and dilution series.