Codon Chart (Standard Genetic Code)

All 64 mRNA codons and the amino acids they encode. For DNA, read T in place of U. Start: AUG · Stop: UAA, UAG, UGA.

1st ↓ / 2nd →	U	C	A	G
U	`UUU` Phe `UUC` Phe `UUA` Leu `UUG` Leu	`UCU` Ser `UCC` Ser `UCA` Ser `UCG` Ser	`UAU` Tyr `UAC` Tyr `UAA` Stop `UAG` Stop	`UGU` Cys `UGC` Cys `UGA` Stop `UGG` Trp
C	`CUU` Leu `CUC` Leu `CUA` Leu `CUG` Leu	`CCU` Pro `CCC` Pro `CCA` Pro `CCG` Pro	`CAU` His `CAC` His `CAA` Gln `CAG` Gln	`CGU` Arg `CGC` Arg `CGA` Arg `CGG` Arg
A	`AUU` Ile `AUC` Ile `AUA` Ile `AUG` Met (start)	`ACU` Thr `ACC` Thr `ACA` Thr `ACG` Thr	`AAU` Asn `AAC` Asn `AAA` Lys `AAG` Lys	`AGU` Ser `AGC` Ser `AGA` Arg `AGG` Arg
G	`GUU` Val `GUC` Val `GUA` Val `GUG` Val	`GCU` Ala `GCC` Ala `GCA` Ala `GCG` Ala	`GAU` Asp `GAC` Asp `GAA` Glu `GAG` Glu	`GGU` Gly `GGC` Gly `GGA` Gly `GGG` Gly

DNA / RNA to protein translator

Nucleotide sequence (DNA or mRNA, 5′→3′)

Reading frame

Codons for each amino acid

Amino acid	Codes	mRNA codons	#
Alanine	Ala / A	`GCU, GCC, GCA, GCG`	4
Arginine	Arg / R	`CGU, CGC, CGA, CGG, AGA, AGG`	6
Asparagine	Asn / N	`AAU, AAC`	2
Aspartic acid	Asp / D	`GAU, GAC`	2
Cysteine	Cys / C	`UGU, UGC`	2
Glutamine	Gln / Q	`CAA, CAG`	2
Glutamic acid	Glu / E	`GAA, GAG`	2
Glycine	Gly / G	`GGU, GGC, GGA, GGG`	4
Histidine	His / H	`CAU, CAC`	2
Isoleucine	Ile / I	`AUU, AUC, AUA`	3
Leucine	Leu / L	`UUA, UUG, CUU, CUC, CUA, CUG`	6
Lysine	Lys / K	`AAA, AAG`	2
Methionine	Met / M	`AUG`	1
Phenylalanine	Phe / F	`UUU, UUC`	2
Proline	Pro / P	`CCU, CCC, CCA, CCG`	4
Serine	Ser / S	`UCU, UCC, UCA, UCG, AGU, AGC`	6
Threonine	Thr / T	`ACU, ACC, ACA, ACG`	4
Tryptophan	Trp / W	`UGG`	1
Tyrosine	Tyr / Y	`UAU, UAC`	2
Valine	Val / V	`GUU, GUC, GUA, GUG`	4
Stop	—	`UAA, UAG, UGA`	3

Molecular weights and properties of each amino acid are in the amino acid chart.

FAQ

How do you read a codon chart?

Find the first base of the codon in the left column, the second base across the top, and the third base on the right of the row block. The cell gives the amino acid. Example: AUG = Methionine (start).

What is the start codon?

AUG (ATG in DNA) codes for methionine and is the usual start codon.

What are the stop codons?

UAA, UAG and UGA (TAA, TAG, TGA in DNA). They end translation and do not code for an amino acid.

How many codons are there?

64: 61 code for the 20 amino acids and 3 are stop codons. Most amino acids are encoded by more than one codon (the code is degenerate).

What is the difference between a DNA and an RNA codon chart?

They are identical except that RNA uses uracil (U) where DNA uses thymine (T). The translator below accepts either.

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Last updated: 2026-10-02 · Found an error? Report it.