Share 'mail size issues.... half size is considered large envelope?'

while this might be a relatively dumb question that i can just search the web for i am really confused. i sent something directly through the post office yesterday (was a first for me, believe it or not)... and it cost me more than it would've if i used my stamps... and when i look at the receipt it's because they used the rates for LARGE envelopes... see, whenever i send out my half size zines,…