What a weighted list is
A weighted drop table is a list of possible results, each with a number called its weight. A larger weight makes an entry more likely to be picked. The table is used after the game has already decided that something will drop, to choose which thing.
The key point for beginners is that weights are relative. A weight of 50 does not mean 50 percent. It means “50 parts out of the total of all weights”, and you only find the percentage by dividing.
From weights to percentages
The chance of an entry is its weight divided by the sum of all weights.
Here is a small table with weights that happen to total 100:
| Entry | Weight | Chance |
|---|---|---|
| Common | 60 | 60 percent |
| Uncommon | 25 | 25 percent |
| Rare | 10 | 10 percent |
| Epic | 4 | 4 percent |
| Legendary | 1 | 1 percent |
When the total is 100, weights and percentages coincide, which is why some tables look like percentages. Most do not total 100. Consider a second table:
| Entry | Weight | Chance |
|---|---|---|
| Common | 150 | 150 / 250 = 60 percent |
| Uncommon | 60 | 60 / 250 = 24 percent |
| Rare | 25 | 25 / 250 = 10 percent |
| Epic | 10 | 10 / 250 = 4 percent |
| Legendary | 5 | 5 / 250 = 2 percent |
The total is 150 + 60 + 25 + 10 + 5 = 250, and the chances sum to 100 percent. Notice that the legendary weight of 5 here is five times the 1 in the first table, yet its chance is only 2 percent against 1 percent. Always divide by the total before comparing.
How the game picks an entry
A common implementation is to generate a random number between 0 and the total weight, then walk through the list, subtracting each weight until the number falls inside one entry’s range. You do not need to know the code to read the odds, but it explains why order does not matter and why only relative size does.
Why designers like weights
The strength of weights is that tables stay easy to edit. Adding a new entry means choosing its weight; the other chances adjust automatically, because the total grows. With raw percentages, a designer would have to change several numbers to keep everything adding to 100.
The effect on existing entries is worth understanding. Suppose a new item with weight 50 is added to the 250-weight table. The total is now 300 and the legendary chance becomes 5 / 300, about 1.67 percent, down from 2 percent. Every other entry shrinks by the same proportion, 250 / 300, or about 83 percent of its previous value. Adding something to a table always dilutes the others, which matters when players ask why a favourite item feels rarer after an update.
Including a “nothing” entry
Many tables include an entry for no drop. Its weight sits alongside the rest. If the five-entry table above gets a “nothing” weight of 250, the total doubles to 500 and each real item’s chance is halved: legendary becomes 5 / 500 = 1 percent per roll. This is one way the same item list can produce quite different drop rates.
Nested tables multiply
Tables are frequently nested. A first table might choose a category, and a second table inside the category chooses the item. The chance of a specific item is the chance of picking its category times its weight share inside that category.
For example, if a chest has a 20 percent weighted chance of choosing the “gems” table and one gem in that table has 5 percent of that table’s weight, then the item’s chance is 0.20 x 0.05 = 0.01, or 1 percent. If you only see the 5 percent figure, the real chance is five times smaller than it appears. The wider system of how rolls combine is outlined in the overview of how loot drop systems work.
Equal weights versus unequal weights
If all entries have the same weight, each has an equal chance. With ten entries, each is 10 percent. But many designs deliberately use unequal weights, which becomes important when a tier is split across several items. In the case of a tier with a combined 2 percent chance, the item chances inside it are not necessarily equal shares. The way weights relate to rarity levels is covered further in the article on rarity tiers.
What a table does not tell you
A weighted table gives the chance per roll. It does not say how many rolls you get, whether protections change the odds, or what the average wait is. For waiting time, the standard method is to take 1 divided by the chance. For the 2 percent legendary above that is 50 rolls on average, with wide variation around it, as explained in the article on expected attempts. And a fixed-weight table has no memory, so a long run of misses does not raise the chance of a hit.
A beginner’s checklist
- Add up all weights to find the total.
- Divide each weight by the total to get its chance.
- Check whether the table is nested, and multiply through if so.
- Check whether a “nothing” or empty entry exists.
- Remember that adding or removing any entry changes all the others.
With these steps, a list of unfamiliar numbers turns into a clear set of chances, which you can then use to judge how long a goal might take. Real outcomes will still vary from run to run.