GC Content Calculator
Calculate the GC content of your DNA or RNA sequences
DNA GC% Calculation
How to Use
- Paste your DNA sequence (raw text or FASTA) into the input box.
- Review length and base counts, then read the computed GC%.
- If you see unexpected results, remove non-ATCG characters or clean formatting (spaces/newlines are OK).
- Copy/download the output or open Reverse Complement for strand-based checks.
What is GC Content?
GC content (GC%) is the fraction of G and C bases in a DNA/RNA sequence. It is commonly used to assess sequence stability, amplification/sequencing bias, and genomic region differences. If you searched for "gc content caculator", the tool above calculates GC% directly from your input.
- Higher GC% often correlates with increased duplex stability
- GC% can affect PCR annealing and amplification efficiency
- Different organisms/regions may have distinct GC% distributions
Related Reading & Next Steps
Comprehensive Guide to GC Content
What is GC Content in DNA?
In DNA, GC content is the percentage of bases that are G (guanine) or C (cytosine). If you came here for a "gc content caculator", this tool lets you measure that percentage from your sequence so you can compare regions, track quality, and estimate how stable a stretch of DNA might be.
Why is GC Content Important?
GC content matters because it influences melting temperature (Tm), duplex stability, and technical behavior in common assays. A practical starting point is to compute your sequence here (many users find this page by typing "gc content caculator"), then interpret the result in context (organism, region, and experiment). For example, if two organisms both have 70% GC, their AT content is 30%, but that similarity alone does not prove close relatedness.
What is High GC Content?
A GC content above ~60% is often considered high. High-GC regions can be more stable and may form secondary structures, which sometimes makes sequencing or amplification harder. If you suspect a GC-rich target, run it through this "gc content caculator" first, then plan primer design and PCR conditions accordingly.
How Does GC Content Affect PCR?
GC content affects PCR by changing how easily the template strands separate and how likely the sequence is to form secondary structures. High-GC templates can need higher denaturation, optimized annealing, and sometimes additives like DMSO or betaine. Use this "gc content caculator" to quickly flag GC-heavy amplicons before troubleshooting.
Primer GC Content
Primer GC content affects primer Tm and binding specificity. A common guideline is ~40–60% GC with a modest GC clamp near the 3′ end (avoid long runs of G/C). When you evaluate primers, pair your primer checks with this "gc content caculator" for the target region so your design and your template constraints match.
FAQ
What if my sequence contains N or other characters?
The calculation is based on recognizable DNA bases (A/T/C/G). Other characters are ignored, so consider cleaning the input for the most accurate result.
What is the formula for GC%?
GC% = (G + C) / (A + T + G + C) × 100%
Can I use this for RNA?
This calculator focuses on DNA bases (A/T/C/G). For RNA sequences containing U, replace U with T to compute GC% on the equivalent representation.
Example
Paste the example above into this "gc content caculator" to see length, GC%, and base composition.