PREAMBLE:
This thread was created to provide some insight to personal loot drop rates in raids, gathered through months of painstaking data collection. Current results are presented below, along with results from previous expansions for comparison purposes.
HISTORY:
Early on in WoD I created a thread called Personal loot: the hard numbers, intended to give a glimpse into the drop rates of personal loot in raids (see here: http://us.battle.net/wow/en/forum/topic/16283269268#1 ). That thread contained drop rates for the entirety of the 5.4 patch in MoP, as well as the first several weeks of patch 6.0 in WoD. The total data set included a thousand samples over a 46 week period, across 4 different max level characters.
At the end WoD, I created another thread called Personal loot: the hard numbers (WoD edition) using the data compiled throughout WoD (see here: https://us.battle.net/forums/en/wow/topic/20747604696#1). That thread worked with a dataset covering about 1,600 samples over 82 weeks, across 7 different max level characters.
Late in Legion I made yet another thread called Personal loot: the hard numbers (Legion edition) with the data I collected over the course of that expansion (see here: https://us.battle.net/forums/en/wow/topic/20762246215?page=1). The thread covered 81 weeks of data, but I actually collected 99 weeks worth and simply forgot to update the thread when Legion ended (and the thread is now locked since the forum migration, so I can’t update it now).
One major change I made during Legion as a result of feedback was separating out bonus rolls from regular chances at loot. That extra data didn’t end up being super important in Legion (bonus roll chance was roughly the same as regular loot chance), but as you’ll see shortly it presents a great contrast to the BfA numbers.
METHODOLOGY:
My BfA data collection follows the same methodology I used for the Legion data (see link for Legion above), so it provides a direct comparison between the two. But in short, I recorded every loot-eligible event and the actual number of loot drops I got. Because personal loot is now forced upon us in BfA, I got much more data on my main character now than before (when I would be using ML for our guild raids).
So what counts as an loot-eligible event? Here’s the criteria.
This data includes:
- all BfA raid bosses, on any difficulty
- all BfA world bosses
- all bonus roll drops under the above scenarios
This data does not include:
- any drop outside of a raid
- any drops as a result of group loot, need before greed, or master loot (deprecated as of BfA, since PL is forced)
- any trash BoE drops
- any quest items
- any pet or mount drops
I kept track of every attempt at loot (every chance at loot I had under the above listed circumstances), and each piece of actual loot I got. For example, if I killed G’huun in normal and got gold, but then used a bonus roll and got a piece of loot, that would count as two attempts (one for the kill, one for the bonus roll) and one piece of loot. If I killed G’huun again the same week and used another bonus roll, that would be only one more attempt because the kill itself wouldn’t have been eligible for loot, only the bonus roll would count.
Note that the data does not indicate whether or not an item acquired was an upgrade or a duplicate, it merely shows that something dropped.
SUMMARY OF PREVIOUS RESULTS:
MoP (Patch 5.4 only, 35 weeks)
Attempts: 964
Loot: 269
Percentage: 27.9% (269 / 964)
WoD (92 weeks)
Attempts: 1,623
Loot: 538
Percentage: 32.9% (538 / 1,623)
Legion (99 weeks)
Regular loot
Attempts: 3,258
Loot: 918
Percentage: 28.2% (918 / 3,258)Bonus rolls
Attempts: 1,072
Loot: 313
Percentage: 29.2% (313 / 1,072)Overall: 28.4% (1,231 / 4,330)
CURRENT RESULTS:
So without further delay, the BfA numbers. Currently this dataset includes numbers for 6 max level characters, though the majority of the data covers just my priest main and druid alt. It includes data from the very first week of Uldir to the last updated date below.
LAST UPDATED: September 24, 2020 (includes 108 weeks of BfA data!)
Regular loot
Attempts: 3,020
Loot: 764
Percentage: 25.3% (764 / 3,020)Bonus rolls
Attempts: 507
Loot: 202
Percentage: 39.8% (202 / 507)OVERALL: 27.4% (966 / 3,527)
So there you have it. With forced personal loot I’ve gotten loot around 27% of the time, based on over 3,500 samples spread across 108 weeks of raiding on multiple max level characters.
PONDERINGS:
One thing you’ll note if you compare BfA numbers to the Legion numbers is that the overall drop rate is very similar. However, if you break it down into the regular drop rates and the bonus roll drop rates, you’ll notice a huge difference.
Regular loot chance has gone down slightly. But because you now get fewer bonus rolls (2 per week in BfA compared to 3+ in Legion), they massively bumped up the drop chance from bonus rolls. So while you have fewer chances at the loot slot machine, each pull of the lever now has a much higher chance to give you something, making the bonus rolls feel way more rewarding.
Long term the loot acquisition rate is the same. But in the short term, there is definitely a feeling that clicking your bonus roll button is far more impactful than it was before.
CONCLUSION:
There is no conclusion really. The point of collecting all this data was to present the community with the hard numbers behind personal loot, without adding any of my personal biases. Make of it what you will. 
This thread will be updated throughout the course of BfA to reflect the latest data as I collect it.
