Replying to Amount of urine needed for UA in ounces?

yes another drug test thread. searched, nothing about this though. and google was no help cause im too stupid to even know what to search the ENTIRE interweb for. i havent taken one in a while but have one tomorrow (will report back later, fingers crossed lol) and need to know this -
how big of a sample do they require? last time i went i didnt pee enough (silly me) so had to chill there drinking water for 45 minutes or come back. i am pretty much fucked as far as passing/blocking so ive accepted the only way to pass is to use someone elses.
whats the minimum? somewhere around 4 oz i believe?
i dont want to walk around with anymore urine then i need to taped to my gooch.