CodonTableCodonTable

Human Codon Usage Table (Homo sapiens)

See the most used codons, highest-fraction synonymous codons, and full codon usage frequencies for Homo sapiens.

Use frequency to find the most common codons in this organism, and use fraction to compare synonymous codon preference within the same amino acid family.

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.
GAG
Amino acid: E
Fraction 0.58
Freq 40.8
CTG
Amino acid: L
Fraction 0.41
Freq 40.3
CAG
Amino acid: Q
Fraction 0.75
Freq 34.6
AAG
Amino acid: K
Fraction 0.58
Freq 32.9
GAA
Amino acid: E
Fraction 0.42
Freq 29.0
GTG
Amino acid: V
Fraction 0.47
Freq 28.9
GCC
Amino acid: A
Fraction 0.40
Freq 28.5
GAC
Amino acid: D
Fraction 0.54
Freq 26.0

Top Codons by Fraction

Synonymous codons ranked by fraction. Stop codons and single-codon amino acids are excluded.
CAG
Amino acid: Q
Fraction 0.75
Freq 34.6
CAC
Amino acid: H
Fraction 0.59
Freq 14.9
GAG
Amino acid: E
Fraction 0.58
Freq 40.8
AAG
Amino acid: K
Fraction 0.58
Freq 32.9
TAC
Amino acid: Y
Fraction 0.57
Freq 15.6
TTC
Amino acid: F
Fraction 0.55
Freq 20.4
TGC
Amino acid: C
Fraction 0.55
Freq 12.2
GAC
Amino acid: D
Fraction 0.54
Freq 26.0

Preferred Codons by Amino Acid

One preferred codon per amino acid, ranked by frequency to surface practical defaults.
GAG
Amino acid: E
Fraction 0.58
Freq 40.8
CTG
Amino acid: L
Fraction 0.41
Freq 40.3
CAG
Amino acid: Q
Fraction 0.75
Freq 34.6
AAG
Amino acid: K
Fraction 0.58
Freq 32.9
GTG
Amino acid: V
Fraction 0.47
Freq 28.9
GCC
Amino acid: A
Fraction 0.40
Freq 28.5
GAC
Amino acid: D
Fraction 0.54
Freq 26.0
GGC
Amino acid: G
Fraction 0.34
Freq 22.8

Homo sapiens (Mamalian/HEK): (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
0.45
0.55
0.07
0.13
16.9
20.4
7.2
12.6
336,562
406,571
143,715
249,879
TCT
TCC
TCA
TCG
S
S
S
S
0.18
0.22
0.15
0.06
14.6
17.4
11.7
4.5
291,040
346,943
233,110
89,429
TAT
TAC
TAA
TAG
Y
Y
*
*
0.43
0.57
0.28
0.20
12.0
15.6
0.7
0.5
239,268
310,695
14,322
10,915
TGT
TGC
TGA
TGG
C
C
*
W
0.45
0.55
0.52
1.00
9.9
12.2
1.3
12.8
197,293
243,685
25,383
255,512
CTT
CTC
CTA
CTG
L
L
L
L
0.13
0.20
0.07
0.41
12.8
19.4
6.9
40.3
253,795
386,182
138,154
800,774
CCT
CCC
CCA
CCG
P
P
P
P
0.28
0.33
0.27
0.11
17.3
20.0
16.7
7.0
343,793
397,790
331,944
139,414
CAT
CAC
CAA
CAG
H
H
Q
Q
0.41
0.59
0.25
0.75
10.4
14.9
11.8
34.6
207,826
297,048
234,785
688,316
CGT
CGC
CGA
CGG
R
R
R
R
0.08
0.19
0.11
0.21
4.7
10.9
6.3
11.9
93,458
217,130
126,113
235,938
ATT
ATC
ATA
ATG
I
I
I
M
0.36
0.48
0.16
1.00
15.7
21.4
7.1
22.3
313,225
426,570
140,652
443,795
ACT
ACC
ACA
ACG
T
T
T
T
0.24
0.36
0.28
0.12
12.8
19.2
14.8
6.2
255,582
382,050
294,223
123,533
AAT
AAC
AAA
AAG
N
N
K
K
0.46
0.54
0.42
0.58
16.7
19.5
24.0
32.9
331,714
387,148
476,554
654,280
AGT
AGC
AGA
AGG
S
S
R
R
0.15
0.24
0.20
0.20
11.9
19.4
11.5
11.4
237,404
385,113
228,151
227,281
GTT
GTC
GTA
GTG
V
V
V
V
0.18
0.24
0.11
0.47
10.9
14.6
7.0
28.9
216,818
290,874
139,156
575,438
GCT
GCC
GCA
GCG
A
A
A
A
0.26
0.40
0.23
0.11
18.6
28.5
16.0
7.6
370,873
567,930
317,338
150,708
GAT
GAC
GAA
GAG
D
D
E
E
0.46
0.54
0.42
0.58
22.3
26.0
29.0
40.8
443,369
517,579
577,846
810,842
GGT
GGC
GGA
GGG
G
G
G
G
0.16
0.34
0.25
0.25
10.8
22.8
16.3
16.4
215,544
453,917
325,243
326,879
Showing 64 entries for Homo sapiens (Mamalian/HEK).
Frequency is measured per 1,000 codons. Fraction compares codons that encode the same amino acid.

Common Searches

Human codon usage table
Homo sapiens codon usage highest fraction
Human preferred codons
Human codon usage frequency table

How To Use This Page

Use the summary cards to find the most used and highest-fraction codons quickly.
Switch sorting in the full table when you want to compare by frequency, fraction, or count.
Use the full organism list and search codons/amino acids on the Codon Usage Frequency Table.

FAQ

What are the most used codons in Homo sapiens?

Use the "Most Used Codons" section to see which codons appear most often in Homo sapiens. The ranking is based on frequency per 1,000 codons.

Which codons have the highest fraction in Homo sapiens?

Use the "Highest Fraction Codons" section to compare synonymous codons for the same amino acid. Single-codon amino acids and stop codons are excluded so the ranking reflects codon preference rather than trivial 1.00 values.

What is the difference between codon frequency and codon fraction in Homo sapiens?

Frequency measures how often a codon appears per 1,000 codons in the dataset. Fraction measures how strongly that codon is preferred relative to alternative codons encoding the same amino acid.

How should I use this Homo sapiens codon usage table for optimization?

Start with the preferred-codon summaries to identify likely defaults, then review the full table below before making codon optimization or expression design decisions.