Codon ChartTranslate a sequence
Paste DNA or RNA, or open a FASTA file with up to 100 records and 30,000 bases total. Select a reading frame and genetic code, then translate every record with those settings. Use Inspect record or the result arrows to move between records. IUPAC ambiguity letters are accepted. Whitespace and position numbers are removed; RNA U is normalized to DNA T internally. Input mixing T and U is rejected so that alphabet mistakes remain visible. Your sequence is processed in this browser and is not uploaded by the tool.
Forward frames +1, +2 and +3 begin at the first, second and third nucleotide. Reverse frames use the reverse complement, then apply the same three offsets. Select all six to compare the possibilities. For a short strand, DNA to mRNA lines up the mRNA, tRNA anticodons and amino acids codon by codon instead. The three-frame worked example shows exactly why shifting the starting base changes the output. A stretch without stop codons can be a useful clue, but this translator does not prove that a sequence is expressed or identify a verified gene.
Inspect bases and amino acids together
The result opens with each frame's protein as plain text: M and * are highlighted for reading, and Copy puts that frame's protein on your clipboard exactly as shown, without spaces or highlighting. Below it, the linked sequence view shows the codons. With several frames, choose Inspect codons on a frame or select its frame card to explore its codons. Each tile connects the three bases to an amino acid. Select a tile to see its full name, exact positions in your original normalized input and any ambiguous assignments. Coordinates on the reverse strand descend. Choose Stops (*) or Unresolved (X) under Show codons to find those assignments without paging through the rest of a long sequence. Tiles keep their original codon numbers and base positions. A codon such as GCN that resolves to one amino acid does not appear in the unresolved view.
Use the arrow keys, Home and End to move among the displayed codons, with up to 60 matches per page. Enter an original codon number under Go to codon to inspect it; this switches to All codons if needed. Changing frames keeps the chosen view. These views cover the translated result, so the stop-before-first-stop setting leaves no definite stop to display. Filtering the view does not shorten copied proteins or downloads.
Codon table TSV downloads every translated codon in all chosen frames, with original coordinates, possible assignments and the NCBI table number. Download FASTA saves every frame's protein. The built-in example is an illustrative 75-base sequence, not a verified natural gene.
Understand the protein output
Protein output uses the one-letter amino-acid alphabet. An asterisk means a definite stop. X means the amino acid cannot be determined uniquely from the available bases or the assignment depends on biological context. The ambiguity comparison distinguishes unresolved codons from definite stops. An ambiguous codon can still resolve: for example, GCN specifies alanine in the standard code because all four possibilities do. Incomplete bases at the end of a frame are reported and left untranslated.
Translation uses internal codon assignments. It does not assume that the first codon is an initiation site or force it to methionine. The optional stop setting ends the result before the first definite stop; it cannot decide a context-dependent stop. Inspect the codon chart or the codon wheel for the exact assignments used by your selected table.
A short translation example
With the standard genetic code and frame +1, ATG GCN TAA translates to MA*: ATG is methionine, every GCN expansion is alanine, and TAA is a stop. Selecting Stop before the first definite stop codon produces MA. This is an illustrative sequence for checking settings, not an identified natural gene.
For a direct comparison, keep frame +1 and enter ATG TGA TAA. The ordinary result is M** in table 1 and MW* in vertebrate mitochondrial table 2. The NCBI code differences explain that change. Set the table from the sequence's biological origin before drawing conclusions from an output.
Save and check your result
Download FASTA writes every record in the selected frame or all six frames, retaining the original name, record number and NCBI table. All records TSV includes each translated codon with its record identity and original coordinates. The TSV button inside the sequence inspector exports the currently displayed record. Duplicate names remain separate through their record numbers. Empty or invalid FASTA records reject the batch rather than disappearing from it. Editing the input or settings clears the previous result, preventing an outdated export from being mistaken for a new calculation. Check the organism, strand, frame and table against your sequence annotation before using a translation in further work.
To examine the input sequence's composition, use the GC content calculator for base counts and a sliding-window profile. For a coding sequence, the host codon usage tables compare synonymous codon choices in three reference datasets.
Inspect complete open reading frames
The built-in ORF finder searches for complete start-to-stop candidates in one record at a time. It is separate from translating every codon in a selected frame: a translation can include incomplete ends or internal stops, while a complete ORF candidate must satisfy the start, stop and minimum-length rules.
Choose a record, then open Inspect open reading frames below the translator to find complete candidates in that record’s six frames. Switching records clears its previous ORF results and exports. Set a minimum protein length and choose ATG-only starts or the selected genetic code's listed starts. Inspect opens a candidate's coding DNA and protein, with Previous ORF and Next ORF to compare candidates. Copy either sequence as plain text, or save that candidate's DNA or protein FASTA with its record identity, frame, coordinates and genetic code. The All proteins FASTA and All coding DNA FASTA buttons save every candidate in the selected record.
Use Copy protein, then paste the candidate into the protein calculator for its molecular weight, pI and extinction coefficient; to turn an A280 reading into a concentration, use the protein concentration calculator on Plasmid Map. Coordinates include the stop codon; reverse-strand candidates run from higher to lower positions. Exported coding DNA always reads 5′ to 3′ on the coding strand, with RNA input normalized to DNA T.
This inspector includes nested starts, excludes partial candidates and treats the input as linear. A codon with an unresolved assignment interrupts a candidate. Context-dependent-stop codes cannot determine complete boundaries here. Candidate proteins begin with M and omit the stop; this differs intentionally from the ordinary translator's internal-codon assignments. Neither result establishes that the candidate is a functional gene. To see whether a candidate's start codon has the bases ribosomes use, check it with the Kozak sequence checker or, for a bacterial gene, the Shine-Dalgarno sequence finder.
The reading-frame overview places complete ORFs on six tracks along your original input. Arrowheads show strand direction. Inspect a result to highlight its span and read the exact DNA, protein and coordinates. Inspect moves keyboard focus to the selected candidate; both sequence boxes can be scrolled with the keyboard, and Back to ORF list returns to its row. Overlapping candidates may cover one another in the overview; each remains listed in the results.
The sources and methods describe the ORF limits and independent comparison checks. NCBI ORFfinder is an independently maintained tool for a separate comparison.