Hi, you may try online method such as:

http://www.endmemo.com/bio/gc.php

Hope this helps.

Hi , you can enter the NCBI or primertree , you can tell by the primers generated sequence and so know the amounts of CGs .

Hi,

You can use this online tool: https://www.idtdna.com/calc/analyzer

You can try this link

http://simgene.com/OligoCalc