stadion sold out

does a sold out stadion means you have to fill it with EXACT the total amount thats capable, or can you stay a little bit under it. like now i have a match against fc twente, 49511 spectators, and the maximum is 51628. can this be accounted as sold out or not?

(againt bigger clubs i got the following number : psv: 51617, feyenoord 51608)

It would not be sold out as they didnt sell all the tickets, so a few seats would be empty.

but would those 4 places really get in the way to expand a stadion? because i got a lot of games (psv, feyenoord, european) that do sell out the stadion.

What matters is the average attendance over the course of the season. If it is high enough, the club has enough funds, the club owns the stadium and the building planning commision (or whatever they are called) says it's ok you might get an expansion.

Im not sure how it works in the game but irl a sell out is when every ticket available to be sold has been slod, its not necesarily every seat has to be filled as some clubs have to keep a number of seats empty for various reasons, like at the milenium stadium for example they have to put netting over a row of seat to separate the fans

my average attendance on february 25 is 49861. the club doesnt own the stadion, but their are enough funds to build a new one (far in the game, some handy transfers etc.)