This is for lvl 70, with a lvl 70 pet starting at Loyalty Level 1 (Newly tamed ravagers). I did some experimenting recently and here is what I discovered. I’ve tested this with a couple of different pets now in SLAB boost and I am pretty sure it’s accurate as during my experiments while running a stop watch, I was only off by a few seconds as to when the loyalty level would increase.
First, you can get loyatly from your pet, even if it is the same level as you. Even at lvl 70. There are 2 requirements. XP and Time.
While we don’t gain XP at level 70 and if your pet is level 70, it doesn’t gain XP either, but there it is still tracked as if you are leveling from 70 to 71. To level from 70 to 71 it takes approximately 1,232,000 xp. To meet the XP requirement for each level of loyalty, your would need to earn 5% of that amount which is around 61,600 xp for each loyalty level. Important, the XP can only come from killing mobs.
The second factor is time. Each loyalty level takes an increasing amount of time with your pet being active and fully fed. Here is the basic rundown showing XP and time.
From Loyalty Level 1 to 2 it takes 61,600 xp (no time requirement)
From Loyalty Level 2 to 3 it takes 61,600 xp and 30 minutes with pet active and fully fed.
From Loyalty Level 3 to 4 it takes 61,600 xp and 45 minutes with pet active and fully fed.
From Loyalty Level 4 to 5 it takes 61,600 xp and 60 minutes with pet active and fully fed.
From Loyalty Level 5 to 6 it takes 61,600 xp and 90 minutes with pet active and fully fed.
You are able to “pre-load” the XP and as soon as you meet the time requirment the loyalty level will increase. This is why sometimes you get an increase in loyalty level while standing around at the auction house doing nothing.
While my experimenting was with lvl 70, at any level if you know how much XP it takes for you to get to the next level and calculate 5% of that, you can figure out the XP requirement part of Loyalty. The only remaining factor would be time.