Paste a DNA or mRNA sequence to translate it into protein in all six reading frames. Stop codons and start codons are highlighted, the longest open reading frame is marked, and you can see the mRNA transcript and a codon-by-codon view.
Last updated:
Amino acid codes
Six-frame translation
StopMet / startLongest ORF
Codon view
Transcription
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How to use the DNA to Protein Translator
Paste your DNA or RNA sequence. FASTA headers, spaces, numbers and line breaks are ignored.
Choose the genetic code (Standard for nuclear genes of most organisms) and 1- or 3-letter output.
Read the six frames. Red asterisks or Stop mark stop codons, green M marks methionine starts, and the shaded stretch is the longest ORF in that frame.
Open a frame in codon view to see each codon aligned with its amino acid and position.
Copy or download one frame, the longest ORF, or all six frames as FASTA.
From DNA to protein: transcription and translation
A gene's coding strand is copied into messenger RNA (transcription), with uracil (U) in place of thymine (T). Ribosomes then read the mRNA three bases at a time (translation). Each three-letter codon stands for one of 20 amino acids or a stop signal. With four bases there are 4 × 4 × 4 = 64 codons, so most amino acids have more than one codon. Translation normally starts at AUG (methionine) and ends at the first in-frame stop codon: UAA, UAG or UGA.
Because the tool reads the coding strand directly, translating DNA gives the same protein as translating its mRNA. Frames −1 to −3 are read from the reverse complement, which is the opposite strand written 5'→3'.
Standard genetic code (NCBI table 1)
Amino acid
3-letter
1-letter
DNA codons
Alanine
Ala
A
GCT, GCC, GCA, GCG
Arginine
Arg
R
CGT, CGC, CGA, CGG, AGA, AGG
Asparagine
Asn
N
AAT, AAC
Aspartic acid
Asp
D
GAT, GAC
Cysteine
Cys
C
TGT, TGC
Glutamine
Gln
Q
CAA, CAG
Glutamic acid
Glu
E
GAA, GAG
Glycine
Gly
G
GGT, GGC, GGA, GGG
Histidine
His
H
CAT, CAC
Isoleucine
Ile
I
ATT, ATC, ATA
Leucine
Leu
L
TTA, TTG, CTT, CTC, CTA, CTG
Lysine
Lys
K
AAA, AAG
Methionine (start)
Met
M
ATG
Phenylalanine
Phe
F
TTT, TTC
Proline
Pro
P
CCT, CCC, CCA, CCG
Serine
Ser
S
TCT, TCC, TCA, TCG, AGT, AGC
Threonine
Thr
T
ACT, ACC, ACA, ACG
Tryptophan
Trp
W
TGG
Tyrosine
Tyr
Y
TAT, TAC
Valine
Val
V
GTT, GTC, GTA, GTG
Stop
Stop
*
TAA, TAG, TGA
Tips for finding the right reading frame
Look for the long ORF. In random sequence a stop codon turns up about once every 21 codons (3 of 64), so an ORF hundreds of codons long is unlikely to be chance.
Check the strand. If the long ORF is in frame −1, −2 or −3, the gene is on the opposite strand. Use the DNA Reverse Complement Tool to flip it.
Mitochondrial genes often look broken under the standard code because TGA means tryptophan there. Switch to table 2 (vertebrates) or 5 (invertebrates).
Bacterial genes can start with GTG or TTG. Tick "Alternative start codons" with table 11 to include them.
Codon view helps when you're checking a point mutation: find the position number and see exactly which codon changed.
Frequently asked questions
How do you translate DNA into protein?
Read the coding strand three bases at a time from a chosen start position. Each three-base codon is looked up in the genetic code to give one amino acid, for example ATG = Met (M), TGG = Trp (W), and TAA, TAG and TGA = stop. The tool replaces T with U for the mRNA view, but the amino acids are the same.
What are the six reading frames?
A DNA sequence can be read in three frames on the given strand, starting at base 1, 2 or 3 (+1, +2, +3), and in three frames on the opposite strand, which is the reverse complement (−1, −2, −3). Only one frame usually encodes the real protein, so six-frame translation is used to find it.
What is an open reading frame (ORF)?
An ORF is a stretch that starts with a start codon (ATG, Met) and continues without a stop codon until it reaches one. Long ORFs are good candidates for protein-coding genes. The tool marks the longest ATG-to-stop ORF in each frame and lets you copy it.
What does X mean in the protein sequence?
X means the amino acid can't be determined, either because the codon contains an ambiguity code (like N) that could give different amino acids or because the codon is incomplete. If every possible base gives the same amino acid, for example GCN = Ala, the tool still shows it.
Which genetic code should I choose?
Use the Standard code (NCBI table 1) for nuclear genes of animals, plants and fungi, and table 11 for bacteria, archaea and plastids (same amino acids, different start codons). Mitochondrial genes use their own tables, for example table 2 for vertebrate mitochondria, where TGA codes for Trp and AGA/AGG are stops.
Can I paste an RNA sequence?
Yes. U and T are treated the same, so mRNA sequences translate directly. The transcription panel shows both the DNA coding strand and the mRNA.
Is my sequence sent to a server?
No. Translation happens in your browser, so unpublished or confidential sequences stay on your device.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.