How to Use the GC Content Calculator
Step 1: Enter or paste your DNA or RNA sequence in the input box. The tool accepts both DNA (A, T, G, C) and RNA (A, U, G, C) sequences.
Step 2: Click Calculate GC Content. Results appear instantly with a visual breakdown of each nucleotide.
Step 3: The large percentage shown is your GC content. Below it you will see individual counts and percentages for each base with colored progress bars.
What is GC Content?
GC content is the percentage of nitrogenous bases in a DNA or RNA molecule that are either Guanine (G) or Cytosine (C). It is one of the most important properties of a nucleic acid sequence.
GC% = (G + C) / Total Bases à 100
// Example: ATGCGATCG (9 bases)
G count = 3, C count = 2
GC% = (3 + 2) / 9 Ã 100 = 55.6%
Why is GC Content Important?
GC content affects many important properties of DNA and RNA including melting temperature, primer design, gene expression, and DNA stability. G-C base pairs form 3 hydrogen bonds while A-T pairs form only 2, making high GC sequences more thermally stable.
GC Content Reference Ranges
| GC Content | Category | Common Example |
|---|---|---|
| 20% â 40% | Low GC | AT-rich regions, TATA box |
| 40% â 60% | Normal / Balanced | Most mammalian genes |
| 50% â 60% | Optimal for PCR primers | Good primer GC range |
| 60% â 80% | High GC | CpG islands, some bacteria |
| Above 80% | Very High GC | Mycobacterium tuberculosis |