Tired of constantly juggling loot in Borderlands 4? Your starting inventory feels painfully small when legendary weapons are dropping left and right. The good news is you can dramatically expand your carrying capacity through the SDU system - but knowing which upgrades to prioritize makes all the difference between efficient vault hunting and constant inventory management headaches.
Borderlands 4 Guide: How to Upgrade Inventory Space and Ammo Capacity
What Are SDU Upgrades in Borderlands 4?
Storage Deck Upgrades (SDU) function as your primary currency for expanding various storage capacities throughout your adventure. Think of SDU tokens as specialized points you'll accumulate by exploring Kairos and completing activities. Unlike skill points, these upgrades are permanent investments that benefit every character on your account.
Borderlands 4 Guide: How to Upgrade Inventory Space and Ammo Capacity
The SDU system covers multiple storage types:
- Backpack - Your personal carrying capacity
- Bank - Shared storage across characters
- Lost Loot - Automatic pickup for missed items
- Ammo capacity - Maximum ammunition reserves
important
SDU upgrades cannot be respecced once purchased, so strategic planning is essential for optimal progression.
Which SDU Upgrades Should You Prioritize?
Your upgrade priority should follow this strategic order based on immediate impact and long-term value:
Backpack Upgrades: Your Top Priority
Backpack expansions deliver immediate relief from inventory constraints. Each upgrade increases your unequipped item slots, letting you carry more weapons, shields, and gear without constant micromanagement. This upgrade directly impacts your moment-to-moment gameplay experience.
Lost Loot Machine: Never Miss Legendaries Again
The Lost Loot upgrade expands your safety net for valuable drops. This machine automatically collects gear you didn't pick up during combat or exploration. With legendary weapons being crucial for endgame builds, missing even one drop can set back your progression significantly.
Bank Storage: Cross-Character Benefits
Bank upgrades create shared storage space accessible by all your characters. This becomes invaluable when you're farming specific gear for different builds or want to transfer powerful weapons between your vault hunters.
Borderlands 4 Guide: How to Upgrade Inventory Space and Ammo Capacity
tip
Bank upgrades become more valuable as you create additional characters, making this a smart long-term investment.
How to Earn SDU Tokens Efficiently
SDU tokens flow from virtually every activity on Kairos, but some sources provide better returns for your time investment:
Primary SDU Sources
Story Progression naturally awards SDU tokens as you advance through campaign missions. You'll receive these automatically without any additional effort required.
Safehouses and Order Silos offer substantial SDU rewards while also unlocking fast travel points. These locations provide dual benefits that make them high-priority targets during exploration.
Borderlands 4 Guide: How to Upgrade Inventory Space and Ammo Capacity
Secondary Collection Methods
Collectibles scattered throughout each region provide steady SDU income:
- Survivalist Caches - Hidden supply containers
- Evocariums - Mysterious energy sources
- Propaganda Speakers - Faction broadcast devices
- Lost Capsules - Emergency supply drops
- Vault Symbols - Ancient markings
Side Objectives and Bounties supplement your SDU earnings while providing combat challenges and exploration incentives.
warning
SDU costs increase with each upgrade tier, so efficient token farming becomes more important as you progress.
Strategic SDU Management Tips
Cost Scaling Considerations
Each subsequent upgrade tier requires more SDU tokens than the previous level. Plan your upgrade path carefully, as the exponential cost increases can strain your token reserves if you spread investments too thin.
Ammo Upgrade Timing
Weapon ammo upgrades provide the least immediate value since ammunition is readily available through vendors and enemy drops. Consider these upgrades only after securing adequate storage capacity for your gear collection.
Character-Specific Needs
Different vault hunter playstyles may benefit from adjusted upgrade priorities. Heavy weapon specialists might value ammo upgrades more than players focused on melee combat or elemental builds.
For more Borderlands 4, take a look at our How to Get Break Free Pack guide.
Borderlands 4 Guide: How to Upgrade Inventory Space and Ammo Capacity