DNA Molecular Weight Calculator
From Sequence Length
Calculate molecular weight from the number of bases or base pairs
From Base Composition
Calculate molecular weight using exact nucleotide counts
Formula
MW(ssDNA) ≈ N × 330 Da. MW(dsDNA) ≈ N × 2 × 330 Da. Exact: MW = nA×331.2 + nT×322.2 + nG×347.2 + nC×307.2 (for single strand).
Frequently Asked Questions
How do you calculate DNA molecular weight?
For a rough estimate, multiply the number of nucleotides by the average nucleotide molecular weight (~330 Da). For dsDNA, multiply by 2 since both strands contribute. A more precise calculation uses exact weights for each base: dAMP=331.2, dTMP=322.2, dGMP=347.2, dCMP=307.2 Da.
What units are used for DNA molecular weight?
DNA molecular weight is expressed in Daltons (Da), kilodaltons (kDa), or megadaltons (MDa). 1 kDa = 1,000 Da. A 1,000 bp dsDNA fragment weighs roughly 660 kDa.
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