DNA to mRNA Calculator — Transcription
Enter a DNA sequence and get the corresponding mRNA strand produced during transcription — with base composition, GC content and codon count.
Input strand type
How does this calculator work?
DNA is transcribed to mRNA by pairing each template-strand base with its RNA complement (A→U, T→A, C→G, G→C). Enter the sequence, choose template or coding strand, and get the mRNA transcript plus GC content, AU content, and codon count in one step.
Formula
How this is calculated
During transcription, RNA polymerase reads the DNA template strand in the 3'→5' direction and synthesises mRNA in the 5'→3' direction. Because mRNA uses uracil (U) instead of thymine (T), each adenine (A) on the template becomes U in the mRNA, each T becomes A, each C becomes G, and each G becomes C — the same complementary base-pairing rules as DNA replication, except U replaces T.
If you already have the coding (sense) strand — which is written in the same direction as the mRNA — switch the mode: the calculator simply replaces every T with U and leaves A, C, and G unchanged. This shortcut is common in molecular biology when a gene sequence (coding strand) is already known and you need to deduce the transcript.
GC content (the fraction of G and C bases) matters because G–C pairs form three hydrogen bonds versus two for A–U, making high-GC regions of mRNA more thermally stable and more prone to secondary structure formation. Codons are non-overlapping triplets counted from the 5' end; the real reading frame begins at the AUG start codon, which this tool does not locate.
Frequently asked questions
The template strand (antisense) is physically read by RNA polymerase — its sequence is complementary and antiparallel to the mRNA. The coding strand (sense) runs 5'→3' in the same direction as the mRNA and has the same sequence, except T replaces U.
Uracil lacks the methyl group that thymine carries, making it cheaper to synthesise. Since mRNA is a transient molecule that is made, used, and degraded quickly, the energy saving of using U rather than T is metabolically advantageous.
Divide the codon count by 1 — but actual protein length depends on the reading frame (starting from AUG) and the position of the stop codon. Translation begins at the first AUG codon and ends at the first in-frame UAA, UAG, or UGA.
Also known as
TG we-Calculate Editorial Team. (2026). DNA to mRNA Calculator — Transcription [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/dna-to-mrna-calculator
TG we-Calculate Editorial Team. "DNA to mRNA Calculator — Transcription." TG we-Calculate. 2026. https://we-calculate.com/calculator/dna-to-mrna-calculator.
TG we-Calculate Editorial Team, "DNA to mRNA Calculator — Transcription," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/dna-to-mrna-calculator
@misc{wecalculate_dna_to_mrna_calculator, title = {DNA to mRNA Calculator — Transcription}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/dna-to-mrna-calculator}}, year = {2026}, note = {TG we-Calculate} }
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