Transcription and Translation Calculator
Transcribe a DNA sequence to mRNA and translate it codon by codon into a protein with the standard genetic code.
If you paste the coding (sense) strand, the mRNA is the same sequence with U in place of T.
How the transcription and translation calculator works
If you paste the coding (sense) strand, the mRNA is the same sequence with U in place of T. If you paste the template strand written 3′→5′, the mRNA is its complement. Translation reads from the first base in triplets — AUG is methionine, UAA, UAG and UGA stop it. Sequences are read in frame 1; trim the start if your open reading frame begins elsewhere.
Formula: mRNA = coding strand with T→U (or the complement of the template strand); protein = codons → standard code
Worked examples
| Inputs | Protein (one-letter) | Note |
|---|---|---|
| Start of the β-globin gene | MVHLTPEE | MVHLTPEE |
| ATG GCC TAA — met, ala, stop | MA | MA, stopped by UAA |
| Template strand TAC CGG ATT | MA | AUG GCC UAA → MA |
FAQFrequently asked questions
Which strand should I paste?
If the sequence starts with ATG and reads like a gene, it is the coding strand — choose that, and the mRNA is the same with U for T. If it is the template strand written 3′→5′, choose template and the calculator takes the complement.
Why does it stop before the end?
It reached a stop codon (UAA, UAG or UGA). If that is earlier than expected, the sequence is probably in the wrong reading frame — remove one or two bases from the start.
What if there is no ATG?
The calculator translates from the first base and does not search for a start codon. Trim the sequence so it begins at your ATG if you want the true open reading frame.
Is this the standard genetic code?
Yes — the universal code used by the nucleus of nearly all organisms. Mitochondria and some microbes differ slightly (UGA is tryptophan in mammalian mitochondria, for instance).
Where these figures come from
- NCBI Bookshelf — Molecular Biology of the Cell — growth kinetics and molecular conventions
- CSIRO — Australia's national science agency
Last checked: September 2026. Formulas are the standard textbook forms; assumptions are stated on each page because they are where these models break.