Josh Liljenquist

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GC Content Calculator

Count A, C, G, and T bases and calculate GC and AT percentages for a DNA sequence.

Calculate

Enter values and run the tool.

Formula and method

GC% = (G count + C count) ÷ total A/C/G/T count × 100. AT% uses the complementary A + T count.

Worked example

AAGCGT contains 3 G/C bases out of 6 total bases, so GC content is 50%.

Limits and assumptions

Strict A/C/G/T input only after removing formatting whitespace. This tool does not infer organism, gene, melting temperature, clinical meaning, or sequencing quality.

Method sources

NCBI MeSH defines GC-rich sequence in terms of guanine and cytosine abundance; the displayed percentage uses the explicit G+C divided by total canonical bases formula.