The bars in login map do approx 8.331959782429537% of your total hp as damage.
A HP Pack in PvP heals a player for approx 9.996703477830888% of your total. Thus for most players it heals around 1k-1.4k HP.
The mob's hp in sector increase by approx 19.1% - 19.99%. Thus with 8 people in the room, the mobs will have approximately a 140% hp increase (2.4 x base hp with 1 person) difference rather than a person soloing it.
Note for the note: Decimals are due to rounding. To find out a good approximate amount just round the % to a whole number (9.99% --> 10%, however do not count the decimal, even it if it > 5 you do not round up.
