Enter your DNA or RNA sequence into the DNA/RNA Molecular Weight Calculator, then set your Sequence Type, Strand Type (single or double), and 5' End State to get the precise Molecular Weight of your oligonucleotide — plus a full breakdown of Sequence Length, GC Content, and individual base counts like A Count and T/U Count.
Molecular Weight
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Sequence Length
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GC Content
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A Count
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T/U Count
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C Count
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G Count
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DNA contains deoxyribose sugar and thymine (T), while RNA contains ribose sugar and uracil (U). RNA is slightly heavier due to the extra hydroxyl group on ribose. The molecular weights are: A=313.2 (DNA)/329.2 (RNA), T=304.2 (DNA)/U=306.2 (RNA), C=289.2 (DNA)/305.2 (RNA), G=329.2 (DNA)/345.2 (RNA).
The 5' end state significantly impacts molecular weight. A 5' hydroxyl adds minimal weight, a 5' phosphate adds approximately 80 Da, and a 5' triphosphate adds about 159 Da to the total molecular weight of the sequence.
The calculator ignores numbers, spaces, and any characters that don't correspond to valid nucleotide bases (A, T, C, G for DNA or A, U, C, G for RNA). Characters like B, Z, or N are filtered out automatically.
GC content is calculated as the percentage of guanine (G) and cytosine (C) bases in the total sequence. It's calculated as: (G count + C count) / total nucleotides × 100%. GC content affects DNA melting temperature and stability.
The calculations use IUPAC standard atomic weights: H=1.00794, C=12.0107, N=14.0067, O=15.9994, P=30.973761 Da. Results are rounded to the nearest hundredth of a Dalton, providing accuracy far beyond typical laboratory requirements.
For double-stranded DNA, the calculator determines the complement sequence and calculates the total weight of both strands. The complementary strand follows base-pairing rules: A pairs with T, and G pairs with C.
This calculator is designed for standard DNA and RNA nucleotides (A, T/U, C, G). Modified nucleotides, unusual bases, or chemical modifications are not supported and should be calculated separately.
Molecular weight is reported in Daltons (Da), which is equivalent to atomic mass units (amu) or grams per mole (g/mol). One Dalton equals approximately 1.66 × 10⁻²⁷ kilograms.