GC Content Calculator

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Introduction

GC Content Calculator — GC% = (G+C) / total bases x 100 for a DNA sequence. Enter DNA sequence to get an instant, accurate result.

Formula

GC content % = (count of G bases + count of C bases) / total sequence length × 100.

Step-by-step

1. Enter the DNA sequence.
2. Click Calculate to see your result instantly.

Real-world example

Example: With DNA sequence = ATGCATGCTAGC, the GC Content Calculator gives Length: 12, Gc Count: 6, Gc Percent: 50.

Frequently Asked Questions

Why does GC content matter?

G-C base pairs form three hydrogen bonds versus two for A-T, so higher GC content generally means a more thermally stable DNA duplex and a higher melting temperature; it also affects PCR primer design and genome sequencing behavior.

What counts toward "total length" if my sequence has non-ACGT characters?

Only valid A, C, G, T letters are kept before the length and GC count are calculated — anything else is stripped out first.

What inputs does the GC Content Calculator need?

You'll need to provide: DNA sequence. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.

How accurate is the GC Content Calculator?

The GC Content Calculator applies the formula exactly as calculated — GC content % = (count of G bases + count of C bases) / total sequence length × 100. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.

Is the GC Content Calculator free to use?

Yes, the GC Content Calculator is completely free, requires no signup, and runs instantly in your browser.

About the GC Content Calculator

The GC Content Calculator uses a real, verifiable formula — GC content % = (count of G bases + count of C bases) / total sequence length × 100. — so results are accurate every time, not an approximation.