GC Content Calculator

Summary

Paste a DNA or RNA sequence to instantly calculate GC content percentage and full nucleotide breakdown.

How it works

1. Paste or type your DNA or RNA sequence into the input field.
2. The tool strips whitespace and converts the sequence to uppercase automatically.
3. Invalid characters are flagged; only A, T, U, G, C are counted.
4. Guanine (G) and cytosine (C) bases are summed, then divided by the total valid base count.
5. Results show GC%, AT/AU%, nucleotide counts, and a visual composition bar.

Use cases

• Check GC content of PCR primers to estimate melting temperature (Tm).
• Assess genome stability — higher GC content generally means higher Tm.
• Quality-check sequences from FASTA files before analysis.
• Compare GC content across different organisms or genes.
• Validate synthetic gene designs for expression optimization.
• Screen sequences for GC-rich secondary structure prone regions.

Frequently Asked Questions