yeah well erh thats not exactly a hard limit thats just your estimated guess.
It all really depends on the server and their rules.
Some servers only allow for x amount of mass some dont have a limit.
POWER 1.0 GUIDELINES:
1million is the most mass most servers can handle, rules or not, but even at those sizes, you need to design your ship head to toe for lag reduction to be able to actually have a same mass fight with someone and not kill your game.
500k is the standard benchmark of where you can still get away with poor lag optimizations and still be fine in a same mass duel. This is the allowed on most servers.
250k it the standard benchmark for if you know you are doing some laggy shit.
POWER 2.0 GUIDELINES:
50k is about as big as you can go without crashing your game once damage and integrity burn start to queue up.
25k is more ideal for lower integrity ships where multiple systems are likely to burn at once.