Minimum players for a Swiss tournament?

What is the minimum players for a 5 round Swiss tournament so it is not auto cancelled on Chess.com?

I run a school chess club, and it is usually at least 4, regardless of the length (I think...someone else may know better.) I believe, in general you need double the number of players to at least complete the # of rounds you want. So if you want a 5 round tournament to actually be 5 rounds, ten players are needed. Otherwise, if you have at least 4, the tournament will happen, but be truncated.

Ex. I schedule a 5 round Swiss, but only 6 players joined, so chess.com truncated it; it ended after 3 rounds.

Thank you so much!  Jet you rock!

1 player = 0 rounds
2 players = 1 round
3-4 players = 2 rounds
5-8 players = 3 rounds
9-16 players = 4 rounds
17-32 players = 5 rounds
33-64 players = 6 rounds
65-128 players = 7 rounds
129-256 players = 8 rounds
257-512 players = 9 rounds