GC content is usually calculated as a percentage value and sometimes called G+C ratio or GC-ratio.

• The GC pair is bound by three hydrogen bonds, while AT pairs are bound by two hydrogen bonds. And so,
• The GC content affects the stability of DNA.
• The GC content affects the secondary structure of mRNA.
• The GC content affects the annealing temperature for template DNA in PCR experiments.

The GC Content can be used in

• primer design for PCR experiments
• gene design from protein expression
• mRNA hairpin prediction and etc.

python GC_content_calc.py /path/to/fasta/file

I have provided an example file of SRY Gene in the example folder. use this file to test the script for better understanding.