In short the Drop Tables show the raw data from the database, before it is pushed through the servers drop algorithm. The Drop Charts are what you as a player can expect to see from a mob, they’re the output of the servers drop algorithm.

Take these drop tables for example:

http://mqemulator.net/npc.php?id=319027&view=droptables

Minimum drop of 1, 2 items with 10% chance each

The server will loop between those two items forever, rolling 10% dice until the minimum drop rate is met. A minimum drop of 1 means that 1 item will always drop. So how could you have an 80% chance of nothing?

So if 1 item drops, and there is only 2 items with a 10% chance each, then it’ll be 50/50 which one you get. Which is what you see on the drop charts:

http://mqemulator.net/npc.php?id=319027&view=dropcharts

If one item was 2% and one was 1% then you’d have 66/33 odds. Same would be true if the chances were actually set to 66% and 33%. The Drop Charts are meant to keep you from having to do the math.

This is a fairly straight forward example but consider the same 10%, 10% but the minimum drop is now 0. That loop only runs until it hits the minimum drop... which is 0. So it’ll only roll each item 1 time. So that would make your odds of 80% nothing, 20% of getting an item. That 20% would have a distribution curve for if you get 1 or 2 of the items. That’s why occasionally some of the drop charts will have a secondary graph showing how many items you are likely to get, and then the pie chart showing what the composition of those items will be.

But wait, it gets worse. There is also a probability on each table, which is a secondary chance that the whole table will even try to drop, and there is a multiplier for how many times the table will try to drop.

There are a lot of calculations that take place on the server, and the values that govern those have been setup by different world builders so the MO changes often. If you know how the drop code works... use the drop tables. If you just want to know as a player what their drop composition will be like use Drop Charts. And lastly, if you’re just after a specific item and what the chance to get that item, use item drop odds.

I should say that while developing the math to do the calculations for the Drop Charts page, I first recoded the servers algorithm in PHP, and I would simulate 10,000 kills and count how many items of each type were dropped, and generate a distribution chart and a pie chart of drop composition. Those trial drops were used to prove the Drop Charts view wasn’t showing the correct real-world data. I didn’t just assume my math was right (it wasn’t at first)

If you’re having an issue where the game doesn’t match let me know. The server code and database data does change regularly so it could require intervention.