Table columns
Use these columns to compare codons within one sequence or across coding sequences.
| Column | Meaning |
|---|---|
| Count | Occurrences of that codon |
| Frequency | Share of all counted codons |
| Per thousand | Normalized usage per 1,000 codons |
Codon Usage Calculator
Paste a coding sequence and get codon frequency, per-thousand usage, amino acid counts, and GC3.
Answer
ATG
Most used codon
Frequency: 13.64%
Count: 3 · Amino acid: Met
Total codons: 22
GC3: 59.09%
Examples
Sequence length
66 bp
Total codons
22
Amino acids
12
Codon usage table
| Codon | Amino acid | Count | Frequency | Per thousand |
|---|---|---|---|---|
| ATG | Met | 3 | 13.64% | 136.4 |
| GCC | Ala | 3 | 13.64% | 136.4 |
| GCT | Ala | 3 | 13.64% | 136.4 |
| GGG | Gly | 2 | 9.09% | 90.9 |
| AAA | Lys | 1 | 4.55% | 45.5 |
| ACT | Thr | 1 | 4.55% | 45.5 |
| CCC | Pro | 1 | 4.55% | 45.5 |
| CTG | Leu | 1 | 4.55% | 45.5 |
| GAA | Glu | 1 | 4.55% | 45.5 |
| GAC | Asp | 1 | 4.55% | 45.5 |
| GAT | Asp | 1 | 4.55% | 45.5 |
| TAA | Stop | 1 | 4.55% | 45.5 |
| TAC | Tyr | 1 | 4.55% | 45.5 |
| TAG | Stop | 1 | 4.55% | 45.5 |
| TTT | Phe | 1 | 4.55% | 45.5 |
Amino acid counts
| Amino acid | Count | Frequency |
|---|---|---|
| Ala | 6 | 27.27% |
| Met | 3 | 13.64% |
| Asp | 2 | 9.09% |
| Gly | 2 | 9.09% |
| Stop | 2 | 9.09% |
| Glu | 1 | 4.55% |
| Leu | 1 | 4.55% |
| Lys | 1 | 4.55% |
| Phe | 1 | 4.55% |
| Pro | 1 | 4.55% |
| Thr | 1 | 4.55% |
| Tyr | 1 | 4.55% |
Formula
Frequency = codon count / total codons; per thousand = frequency x 1000The calculator reads complete codons in the selected frame. Stop codons can be included or excluded from the totals.
| Symbol | Variable | Description |
|---|---|---|
| Codon count | Count | How many times a codon appears in the selected frame. |
| Total codons | Total | Complete codons counted after applying the frame and stop-codon setting. |
| GC3 | Third-position GC | The percentage of codons ending in G or C. |
How to use it
- 1
Paste a coding sequence
Spaces, line breaks, FASTA headers, and non-DNA characters are ignored; U is treated as T.
- 2
Choose the reading frame
Use frame 1 for most coding sequences that start at the first base.
- 3
Read the usage table
The codon table shows count, percentage frequency, and per-thousand usage.
Codon usage FAQ
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