Peptide Sequence Length & Notation Converter
Count residues and peptide bonds, and convert a sequence between one-letter and three-letter amino-acid codes.
Sequence length
Working
About this tool
Count the residues in a sequence, see how many peptide bonds join them, and convert between one-letter and three-letter notation. The formatted view splits long sequences into numbered blocks of ten so they are easier to check against a paper or certificate.
How to use it
- Paste the sequence in either notation. The format is detected automatically, or you can set it.
- Copy the converted sequence or the numbered blocks.
Formula f(x)
bonds = n − 1 for a linear peptide of n residues.
A rough size estimate is M ≈ n × 110 g/mol (average residue mass). Use the molecular weight calculator for an exact value.
Worked example check your setup
Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val converts to GEPPPGKPADDAGLV: 15 residues joined by 14 peptide bonds.