Is there a calculator to determine the size and composition for the generated amplicons given the reverse primer, forward primer, and the DNA they were used on?
First: go to https://blast.ncbi.nlm.nih.gov/Blast.cgi?PAGE_TYPE=BlastSearch
Second: enter your primer and forward sequences primer in the top box with the following format: "forwardprimernnnnreverseprimer" example: "ACATGCCGTCACCnnnnCACTTGAATTGCAC"
please bear in mind that the reverse primer must be entered as the reverse complement. You can use http://reverse-complement.com/
Third: click the blast button at the bottom and wait until the result appear.
fourth: click the top one in the result as it has the most similarity. Then just subtracting the range1-range2.
It is very helpful: https://www.youtube.com/watch?v=04t6PbopFas