DNA Molecular Weight Calculator
DNA Molecular Weight Calculator computes the molecular weight of a DNA sequence (single-stranded or double-stranded) in Daltons. Input a DNA sequence, select strand type and 5′ phosphorylation, and calculate the molecular weight.
Enter Parameters
How to Use DNA Molecular Weight Calculator:
- Enter a DNA sequence (A, T, C, G, case-insensitive) using the keypad or direct input; use “Next” to switch fields.
- Select strand type (single-stranded or double-stranded) and whether the 5′ end is phosphorylated.
- Click “Calculate” to see the molecular weight and step-by-step breakdown.
- Use “Share Result” to share or “Export Result” to download as a text file.
Formula:
Single-stranded DNA (ssDNA):
MW = Σ(nucleotide weights) – (n-1) × 18 + (79.0 if 5′ phosphorylated)
Double-stranded DNA (dsDNA):
MW = [Σ(nucleotide weights, forward) – (n-1) × 18 + (79.0 if 5′ phosphorylated)] + [Σ(nucleotide weights, reverse) – (n-1) × 18 + (79.0 if 5′ phosphorylated)]
Where: MW = molecular weight (Da), n = sequence length, nucleotide weights: A=313.2, T=304.2, C=289.2, G=329.2 Da.
Important Notes:
- Sequence must contain only A, T, C, G (case-insensitive) and be 1-10,000 bases long.
- Weights are approximate averages for deoxyribonucleotides. Actual weights may vary slightly due to isotopic composition.
- Phosphodiester bonds remove one water molecule (18 Da) per bond. 5′ phosphorylation adds 79.0 Da per strand.
- Clipboard access requires HTTPS. If exporting fails, try accessing over HTTPS or copy manually.
- Results are for standard DNA; modified nucleotides or RNA require different weights.