DNA to RNA Transcription Calculator
Turn a DNA sequence into its complementary strand and the transcribed mRNA, swapping every T for a U.
Paste a DNA sequence and get its complementary strand plus the transcribed mRNA. A pairs with T, G pairs with C, and transcription swaps every T for a U. Spaces are ignored and letters are uppercased automatically.
Complementary DNA strand
TACGCATG
mRNA (T → U)
AUGCGUAC
How it works
DNA bases pair up in a fixed way: A with T, and G with C. The complementary strand is just your sequence with each base swapped for its partner.
Transcription copies DNA into messenger RNA, which uses uracil (U) wherever DNA would use thymine (T). So the mRNA shown here is your sequence with every T rewritten as U.
Type or paste a sequence in any mix of case, with or without spaces. The tool tidies it up — uppercasing and stripping whitespace — and only accepts the four DNA bases, flagging anything else.
Frequently asked questions
What's the difference between the two outputs?
The complementary strand is still DNA (it uses T), showing the base that pairs with each of yours. The mRNA is the transcribed RNA copy, which reads the same as your input strand but with every T turned into U.
Why did it reject my sequence?
It only accepts A, C, G and T. Ambiguity codes like N or R, protein letters, or stray punctuation aren't allowed, so the tool points out the unexpected character instead of guessing.
Does capitalization or spacing matter?
No. Lowercase letters are uppercased and spaces and line breaks are removed before anything is computed, so you can paste a formatted sequence straight in.