You set your backpack to 100 slots in Gibbed, save, load the game — and you're back to 39. It's not a bug in the editor, and you're not doing it wrong exactly. Gearbox patched the inventory-size exploit years ago, so the game now clamps your slot count back to the legitimate maximum on load. The good news: there's a proper way to expand it that does stick.
- Don't type a raw slot number — the game resets it.
- Raise it through Raw tab → BlackMarketUpgrades → the inventory SDU instead.
- Backpack size = 12 + 3 × (SDUs), up to the legit max (around 39).
Why it resets
Your backpack size isn't a free number — the game computes it from how many Storage Deck Upgrades (SDUs) you've bought: 12 base slots + 3 per SDU. When you set a raw slot count higher than your SDUs justify, the game's sanity check sees an impossible value and recomputes it back down to what your SDUs actually allow. That's the "back to 39" you keep landing on.
This used to be exploitable by editing the slot count directly — until a patch (around the 1.2.0 era) closed it. So old tutorials that say "just set the slots field" don't work anymore. The slot field isn't the lever; the SDU count is.
This is the sanity check again — an impossible value getting rolled back to a legitimate one. Make it legitimate and it sticks.
The right way: edit the SDUs
Instead of the slot count, raise the underlying upgrade count. In the editor's Raw tab → BlackMarketUpgrades, the inventory SDU value is what the game multiplies out into slots. Bump that, and the game happily gives you 12 + 3 × SDUs — because now the number is "earned," as far as it's concerned. The Raw tab and SDUs are covered in detail in tabs explained.
The honest limit
Here's the part nobody wants to hear: there's a ceiling, and you can't blow past it. The legitimate maximum backpack lands around 39 slots (some sources put the full-SDU total a touch higher) — and beyond that, no edit holds. The exploit that gave hundreds of slots is patched dead. So if you set the SDUs to the max and still want more space, the answer is: there isn't any more to give.
Want more room anyway?
Two real options, since a bigger backpack isn't on the table:
- Use the Bank. It's separate storage, and you can expand it the same way (its own SDU). Stash what you're not carrying.
- Be ruthless. Delete duplicates and junk in the Backpack tab. With a maxed backpack and bank, most people have plenty of room once they stop hoarding whites.
Quick answers
Why does my backpack reset to 39?
How do I actually get more slots?
Can I get 100+ slots like old guides show?
The Borderlands Wiki Storage Deck Upgrade page (12 + 3 × SDU), the Se7enSins "how to mod backpack space" thread (the Raw/BlackMarketUpgrades method and the patch that broke direct edits), and the community's long-standing "resets to 39" reports. Checked June 2026.