Codon Chart

A FIELD GUIDE TO THE GENETIC CODE

Sources & methods.

A reference you can inspect, with explicit choices about ambiguity and context.

Genetic-code data

The 27 tables come from NCBI's genetic-code reference, retrieved September 26, 2026. The source page identifies its last update as September 23, 2024. Data generation preserves each table's 64 amino-acid assignments, initiation markers and context-dependent termination markers. NCBI table identifiers are retained throughout the interface and sequence exports.

Translation and sequence handling

Codons are read 5′ to 3′. Negative reading frames use the reverse complement. IUPAC ambiguity is expanded into its possible unambiguous codons; the output is a residue only if all possibilities agree. Context-dependent termination produces X in a translated sequence and an explicit note in the chart. This translator does not infer initiation or specialized recoding. Input is limited to one sequence and 30,000 bases.

Side-chain categories are broad teaching groups rather than predictions of protonation in a particular protein. Stop signals are separate from the 20 standard amino acids. Protein output uses the ordinary one-letter alphabet, * for definite termination, and X for unresolved assignments.

Downloads

SVG charts contain vector shapes and text. The chosen genetic code and alphabet determine their labels. FASTA downloads identify the selected operation or translation frame. The charts are generated for this site; they do not reproduce a third-party chart illustration.

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