CodonTableCodonTable

Codon Usage Frequency Table

Compare organisms, review the top codons by frequency or fraction, and search the full codon usage table.

Frequency is expressed as the number of times each codon appears per 1,000 codons. Fraction compares synonymous codons for the same amino acid. Data is compiled from genomic databases including CUTG (Kazusa DNA Research Institute).

Learn how genetic code variants affect translation →
E. coli codon usage tableHuman codon usage tableYeast codon usage tableArabidopsis codon usage

Choose Organism and Display

These settings control the summary cards and the full codon usage table below.

Top Codons by Frequency

Codons ranked by frequency per 1,000 codons in the selected organism.
CTG
Amino acid: L
Fraction 0.47
Freq 48.4
GAA
Amino acid: E
Fraction 0.68
Freq 39.1
AAA
Amino acid: K
Fraction 0.74
Freq 35.3
GAT
Amino acid: D
Fraction 0.63
Freq 32.7
GCG
Amino acid: A
Fraction 0.33
Freq 30.1
ATT
Amino acid: I
Fraction 0.49
Freq 29.8
CAG
Amino acid: Q
Fraction 0.66
Freq 28.4
GGC
Amino acid: G
Fraction 0.37
Freq 27.1

Top Codons by Fraction

Synonymous codons ranked by fraction. Stop codons and single-codon amino acids are excluded.
AAA
Amino acid: K
Fraction 0.74
Freq 35.3
GAA
Amino acid: E
Fraction 0.68
Freq 39.1
CAG
Amino acid: Q
Fraction 0.66
Freq 28.4
GAT
Amino acid: D
Fraction 0.63
Freq 32.7
TAT
Amino acid: Y
Fraction 0.59
Freq 17.5
TTT
Amino acid: F
Fraction 0.58
Freq 22.1
CAT
Amino acid: H
Fraction 0.57
Freq 12.5
TGC
Amino acid: C
Fraction 0.54
Freq 6.1

Preferred Codons by Amino Acid

One preferred codon per amino acid, ranked by frequency to surface practical defaults.
CTG
Amino acid: L
Fraction 0.47
Freq 48.4
GAA
Amino acid: E
Fraction 0.68
Freq 39.1
AAA
Amino acid: K
Fraction 0.74
Freq 35.3
GAT
Amino acid: D
Fraction 0.63
Freq 32.7
GCG
Amino acid: A
Fraction 0.33
Freq 30.1
ATT
Amino acid: I
Fraction 0.49
Freq 29.8
CAG
Amino acid: Q
Fraction 0.66
Freq 28.4
GGC
Amino acid: G
Fraction 0.37
Freq 27.1

Escherichia coli (E.coli): (Genetic code: Standard)

Print-friendly 2-column table in genetic code order. Frequency is shown per 1,000 codons.
TripletAmino acidFractionFrequency/ThousandNumberTripletAmino acidFractionFrequency/ThousandNumber
TTT
TTC
TTA
TTG
F
F
L
L
0.58
0.42
0.14
0.13
22.1
16.0
14.3
13.0
80,995
58,774
52,382
47,500
TCT
TCC
TCA
TCG
S
S
S
S
0.17
0.15
0.14
0.14
10.4
9.1
8.9
8.5
38,027
33,430
32,715
31,146
TAT
TAC
TAA
TAG
Y
Y
*
*
0.59
0.41
0.61
0.09
17.5
12.2
2.0
0.3
63,937
44,631
7,356
989
TGT
TGC
TGA
TGG
C
C
*
W
0.46
0.54
0.30
1.00
5.2
6.1
1.0
13.9
19,138
22,188
3,623
50,991
CTT
CTC
CTA
CTG
L
L
L
L
0.12
0.10
0.04
0.47
11.9
10.2
4.2
48.4
43,449
37,347
15,409
177,210
CCT
CCC
CCA
CCG
P
P
P
P
0.18
0.13
0.20
0.49
7.5
5.4
8.6
20.9
27,340
19,666
31,534
76,644
CAT
CAC
CAA
CAG
H
H
Q
Q
0.57
0.43
0.34
0.66
12.5
9.3
14.6
28.4
45,879
34,078
53,394
104,171
CGT
CGC
CGA
CGG
R
R
R
R
0.36
0.36
0.07
0.11
20.0
19.7
3.8
5.9
73,197
72,212
13,844
21,552
ATT
ATC
ATA
ATG
I
I
I
M
0.49
0.39
0.11
1.00
29.8
23.7
6.8
26.4
109,072
86,796
24,984
96,695
ACT
ACC
ACA
ACG
T
T
T
T
0.19
0.40
0.17
0.25
10.3
22.0
9.3
13.7
37,842
80,547
33,910
50,269
AAT
AAC
AAA
AAG
N
N
K
K
0.49
0.51
0.74
0.26
20.6
21.4
35.3
12.4
75,436
78,443
129,137
45,459
AGT
AGC
AGA
AGG
S
S
R
R
0.16
0.25
0.07
0.04
9.9
15.2
3.6
2.1
36,097
55,551
13,152
7,607
GTT
GTC
GTA
GTG
V
V
V
V
0.28
0.20
0.17
0.35
19.8
14.3
11.6
24.4
72,584
52,439
42,420
89,265
GCT
GCC
GCA
GCG
A
A
A
A
0.18
0.26
0.23
0.33
17.1
24.2
21.2
30.1
62,479
88,721
77,547
110,308
GAT
GAC
GAA
GAG
D
D
E
E
0.63
0.37
0.68
0.32
32.7
19.2
39.1
18.7
119,939
70,394
143,353
68,609
GGT
GGC
GGA
GGG
G
G
G
G
0.35
0.37
0.13
0.15
25.5
27.1
9.5
11.3
93,325
99,390
34,799
41,277
Showing 64 entries for Escherichia coli (E.coli).
Frequency is measured per 1,000 codons. Fraction compares codons that encode the same amino acid.

How To Use This Table

Start by selecting an organism, then use the summary cards to see the most used codons, highest-fraction codons, and preferred codons by amino acid.

Use the table search when you want to jump directly to a codon or amino acid, and switch sorting when you want to compare by frequency, fraction, or count.

Codon usage bias matters for:

  • Optimizing gene expression in heterologous hosts.
  • Predicting gene expression levels.
  • Evolutionary studies.

Data Sources

The data presented here is derived from large genomic databases. The main reference source is Codon Usage Tabulated from GenBank (CUTG), maintained by the Kazusa DNA Research Institute.

This page is designed for quick comparison across common expression hosts such as E. coli, yeast, human, and Arabidopsis, while the organism pages provide a more focused landing page for each species.