GC Content Calculator
Calculate GC content of a sequence and the melting temperature it implies.
About GC Content Calculator
GC content determines duplex stability because GC pairs have three hydrogen bonds to AT’s two. It also predicts melting temperature and correlates with genome organisation across organisms. GC-rich templates form secondary structures that resist amplification, which is why they often require DMSO or betaine additives.
Formula
GC Content
GC % = (G + C) ÷ total bases × 100
- GC content
- Share of bases that are guanine or cytosine
Worked example
With the default values below, GC Content Calculator returns GC Content of 48.000%. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Number of G and C basesminimum 0
- 24
- Total sequence lengthminimum 1 bases
- 50 bases
Results
- GC Content
- 48.000%
- AT Content
- 52.000%
- GC to AT Ratio
- 0.92308
- Estimated Melting Temperature
- 71.132 C
- Verdict
- Balanced composition suitable for standard protocols
Step by step
- 1Values used
- 2GC Content
- 3GC Content= 48.000
- 4AT Content= 52.000
- 5GC to AT Ratio= 0.92308
- 6Estimated Melting Temperature= 71.132 C
- 7Verdict= Balanced composition suitable for standard protocols
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is GC Content calculated?
GC % = (G + C) ÷ total bases × 100 GC content determines duplex stability because GC pairs have three hydrogen bonds to AT’s two. It also predicts melting temperature and correlates with genome organisation across organisms.
Why does GC Content matter?
GC-rich templates form secondary structures that resist amplification, which is why they often require DMSO or betaine additives.
What values do I need to enter?
This calculator takes 2 inputs: Number of G and C bases, Total sequence length. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.