Backpacks and Inventory
Slot counts for every backpack at every quality, and what it takes to carry a full one at full speed. All numbers come from the game files.
Your inventory is an 8 by 6 grid of 48 slots. The top 32 are free to use. The bottom 16 are encumbered, and each item sitting in one costs 1.1% of your movement speed, down from 2.6% per slot in V3.2. A backpack goes in the new Backpack equipment slot and adds more encumbered rows, up to 96 slots.
Fill all 96 with nothing that frees slots and 64 of them are encumbered, a 70% slowdown. A big pack is only worth carrying alongside the free-slot sources further down this page.
Each size comes in quality 1 to 6. The top number is the slots it adds and the one under it is your total with it equipped. A Q1 of the bigger size still beats a Q6 of the smaller one, so go up a size before chasing quality.
| Backpack | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 |
|---|---|---|---|---|---|---|
 Small Backpack | +2 50 | +4 52 | +6 54 | +8 56 | +12 60 | +16 64 |
 Medium Backpack | +18 66 | +20 68 | +22 70 | +24 72 | +28 76 | +32 80 |
 Large Backpack | +34 82 | +36 84 | +38 86 | +40 88 | +44 92 | +48 96 |
Encumbrance counts slots, not weight. Each of these turns encumbered slots into free ones:
| Source | Free slots |
|---|---|
| Pack Mule perk, ranks 1 to 5 (Strength 1 to 5) | +4 / +12 / +24 / +40 / +56 |
| Armor Pocket Mod per armor piece | +1 |
| Armor Double Pocket Mod per armor piece | +2 |
| Armor Triple Pocket Mod per armor piece | +3 |
| Armor Quad Pocket Mod per armor piece | +4 |
| Lumberjack Outfit Q1 to Q6 | +1 to +10 |
| Scavenger Outfit Q1 to Q6 | +1 to +10 |
| Nomad Outfit Q1 to Q6 | +1 to +10 |
| Chicken Nuggets while the buff lasts | +48 |
| Steroids while the buff lasts | all 96 |
Pack Mule at rank 5 gets you to 88 free slots. Clearing the last 8 of a full 96-slot pack takes 2 Armor Quad Pocket Mods, or a Q6 outfit from the list above on its own.
Reading Pack Rat Magazines levels the backpack crafting skill from 0 to 100. Small Backpacks unlock at skill 5 (Q6 at 30), Medium at 40 (Q6 at 65) and Large at 75 (Q6 at 100). All three are made at a workbench, and the ingredient list grows with the quality you craft:
| Ingredient | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 |
|---|---|---|---|---|---|---|
 Sewing Kit | 1 | 2 | 3 | 4 | 5 | 6 |
 Cloth Fragment | 5 | 10 | 15 | 20 | 25 | 25 |
 Forged Iron | - | - | - | 1 | 3 | 5 |
| Ingredient | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 |
|---|---|---|---|---|---|---|
| Sewing Kit | 7 | 8 | 9 | 10 | 11 | 12 |
 Leather | 25 | 30 | 35 | 40 | 45 | 50 |
| Forged Iron | 5 | 10 | 15 | 20 | 25 | 30 |
| Ingredient | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 |
|---|---|---|---|---|---|---|
| Sewing Kit | 13 | 14 | 15 | 16 | 17 | 18 |
| Leather | 50 | 55 | 60 | 65 | 70 | 75 |
 Scrap Polymers | 20 | 35 | 50 | 65 | 80 | 95 |
 Forged Steel | 5 | 10 | 15 | 20 | 25 | 30 |
 Legendary Parts | - | - | - | - | - | 1 |
Backpacks drop from one container: the Savage Country Box. Each box rolls the backpack table 9.4% of the time, and your loot stage picks the size: Small Backpacks from loot stage 30 (most common at 68, gone after 107), Medium Backpacks from loot stage 88 (most common at 126, gone after 165), Large Backpacks from loot stage 146 (most common at 184). None of the trader stock tables in the V3.3 files list a backpack, so plan on crafting or looting one.
Pack Rat Magazines are much easier to find: soldier zombie loot bags carry one 21.7% of the time, thug loot bags 17%, Savage Country Boxes 14.5%, and the standard traders sell them. Every Pack Mule rank also raises your odds of finding one until the skill reaches 100.