Paste a DNA or RNA sequence and this free DNA sequence calculator returns its complement and reverse complement, transcribes DNA to mRNA, translates the codons into a protein sequence, and reports base counts, GC content, melting temperature (Tm) and molecular weight. Ideal for biology homework and primer checks.
From DNA to protein
The coding strand has the same sequence as the mRNA (with T instead of U). The template strand is the one RNA polymerase actually reads, so the mRNA is its reverse complement. Choose which one you pasted and the calculator transcribes it correctly.
GC content, Tm and molecular weight
Higher GC content means more hydrogen bonds (three per G–C pair, two per A–T), so higher melting temperature. PCR primers usually aim for 40–60% GC and a Tm of 52–65 °C. These Tm values are estimates; salt and primer concentration change real results.
Frequently asked questions
How do I convert DNA to mRNA?
If you have the coding strand, replace every T with U. If you have the template strand, take the reverse complement and replace T with U. Choose the strand type and the calculator does it for you.
How do I translate mRNA into a protein?
Read the mRNA three bases (one codon) at a time from the start codon AUG and look each codon up in the genetic code until you reach a stop codon. The calculator shows the one-letter and three-letter amino acid sequence.
What is a reverse complement?
It is the sequence of the opposite DNA strand read in the 5′ to 3′ direction: complement each base (A↔T, G↔C) and reverse the order. It’s used for primers and searching both strands.
How is GC content calculated?
Count G and C bases, divide by the total number of bases and multiply by 100. The calculator also shows counts of every base.
Which genetic code does it use?
The standard genetic code (NCBI table 1), used by most nuclear genes. Mitochondrial and some microbial genes use slightly different codes.
Related tools
Free educational tool by HawkInc. Results are calculated in your browser and rounded for display; check critical work by hand or with a second method.