Codon Table — DNA & RNA Genetic Code Chart

Common codon lookups

Quick answers for common RNA and DNA codon-to-amino-acid searches. RNA codons use U; the equivalent DNA codons use T.

Start and stop codons

Translation begins at the start codon AUG (ATG in DNA), which also codes for methionine — that is why most proteins start with Met. It ends at one of the three stop codons, UAA, UAG or UGA, which do not encode any amino acid and release the finished polypeptide.

DNA vs RNA codons

The DNA and RNA codon tables are identical except that RNA uses uracil (U) wherever DNA uses thymine (T). During transcription the DNA coding strand is copied base-for-base into mRNA, with T replaced by U. See DNA vs RNA for the full picture.

Amino acids and their codons

All 20 standard amino acids, with their one- and three-letter codes, side-chain class and every codon that encodes them.

Codons for one amino acid

The table above reads codon to amino acid. To go the other way — which codons encode a given residue, and which one your expression host actually prefers — each amino acid has its own page.

Learn more

• Amino Acids Chart — codes, classes and properties →
• Reading Frames and Open Reading Frames (ORFs), Explained →
• Codon Optimization Explained →
• DNA vs. RNA: Differences in Structure, Bases and Function →

Sources

1. 1
   The Genetic Codes (NCBI Taxonomy) — transl_table 1, The Standard Code

   Elzanowski A, Ostell J · NCBI, National Library of Medicine · Last update of the Genetic Codes: 23 September 2024 (accessed 13 September 2026)

   The entire 64-codon grid rendered by CodonTableView (STANDARD_CODON_TABLE in src/lib/bio/translate.ts); the header claim '61 sense codons for 20 amino acids, one start codon AUG, three stop codons UAA/UAG/UGA'; the 'Codons (DNA)' column of the 'Amino acids and their codons' table including the Stop row; and all 11 rows of the 'Common codon lookups' table (UGG=Trp, GAG=Glu, UAA=Stop, etc.). Also the FAQ answers on the start codon, the stop codons and the 61/20 degeneracy count.
2. 2
   Nomenclature and Symbolism for Amino Acids and Peptides (Recommendations 1983), section 3AA-21.2 'The Code Symbols'

   IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN) · Eur J Biochem 138:9-37 (1984); also Biochem J 219:345-373 and Pure Appl Chem 56:595-624 · 1983/1984

   The '3-letter' and '1-letter' columns and the full amino-acid names in the 'Amino acids and their codons' table (AA_THREE_LETTER and AA_NAMES), the 'Code' column of the Common codon lookups table (Trp / W, Glu / E, …), and the FAQ answers 'What amino acid is UGG?' and 'What amino acid is GAG?' including the Glu = glutamate/glutamic acid naming.
3. 3
   Codon-anticodon pairing: the wobble hypothesis

   Crick FHC · J Mol Biol 19(2):548-555 · 1966

   One sentence only: the FAQ answer 'Why do several codons code for the same amino acid?', specifically the clause 'Synonymous codons usually differ in the third "wobble" position.' It backs nothing else on the page.

Related tools and references