RNA Molecular Weight Calculator
FREE TOOL
0 valid bases
Accepts .txt, .fasta, .fa files — FASTA headers removed automatically
0
g/mol (Daltons)
0 kDa
Kilodaltons
0 nt
Sequence Length
dsRNA
Strand Type
Nucleotide Contribution Breakdown
How to Use the RNA Molecular Weight Calculator
Step 1: Enter your RNA sequence in the input box above.
Step 2: Select whether your sequence is single stranded or double stranded RNA.
Step 3: Select the end type — most laboratory RNA uses a 5' phosphate group by default.
Step 4: Click Calculate MW. The result shows molecular weight in g/mol, kDa, and a breakdown by nucleotide contribution.
How RNA Molecular Weight is Calculated
The molecular weight of an RNA sequence is calculated by summing the molecular weights of all individual ribonucleotides and subtracting water molecules lost during phosphodiester bond formation. RNA uses uracil (U) instead of thymine (T), and complementary base pairing uses A–U.
// Monoisotopic MW of RNA nucleotides (5' phosphate):
AMP (Adenine) = 347.22 g/mol
UMP (Uracil) = 324.18 g/mol
GMP (Guanine) = 363.21 g/mol
CMP (Cytosine) = 323.20 g/mol
// Formula for ssRNA:
MW = (nA × 347.22) + (nU × 324.18) +
(nG × 363.21) + (nC × 323.20) - (n - 1) × 18.02
// For dsRNA — add complement strand MW using A-U pairing
AMP (Adenine) = 347.22 g/mol
UMP (Uracil) = 324.18 g/mol
GMP (Guanine) = 363.21 g/mol
CMP (Cytosine) = 323.20 g/mol
// Formula for ssRNA:
MW = (nA × 347.22) + (nU × 324.18) +
(nG × 363.21) + (nC × 323.20) - (n - 1) × 18.02
// For dsRNA — add complement strand MW using A-U pairing
Reference Molecular Weights
| Nucleotide | Base | MW (5' Phosphate) g/mol | MW (5' OH) g/mol |
|---|---|---|---|
| AMP | Adenine | 347.22 | 267.24 |
| UMP | Uracil | 324.18 | 244.20 |
| GMP | Guanine | 363.21 | 283.24 |
| CMP | Cytosine | 323.20 | 243.22 |