I was three runs in when the final Sponsor kit slipped from my hands and refused to fit—my vault was full. I stared at the stash screen while my heart sunk; you know that small panic when a haul you earned is about to be lost. My inventory felt like a coat closet stuffed with winter coats, and I had to act fast.
I’ll tell you exactly what I do when my loadout threatens to bury me. You’ll get the short route to more space, what to buy first, and how to avoid wasting Credits and parts. I play this like a small economy—so you can treat every run like a profit-and-loss decision.
How to increase your Vault size in Marathon
On a solid session I realized the vault cap was the thing holding my progress back.
Your vault is where everything you keep between runs lives. By default it holds 160 items, and once you start finishing Sponsored kits that number starts to feel laughably small. If you want to keep the rhythm—more loot, fewer sell-offs—you buy the Expansion upgrade from the CyberAcme faction. It’s pure Credits and parts, no gimmicks.
You can expand five times total (that’s current as of the latest patch). Each step costs more Credits and more Unstable parts. Treat this like an investment: the early expansions buy you breathing room; the late ones pay off only if you’re regularly returning with big hauls.
| Upgrade level | Effect | Cost |
|---|---|---|
| 1 | +8 rows | 2500 Credits12 Unstable Diode |
| 2 | +8 rows | 4000 Credits22 Unstable Diode12 Unstable Gunmetal |
| 3 | +6 rows | 5000 Credits27 Unstable Diode15 Unstable Gunmetal |
| 4 | +4 rows | 7000 Credits30 Unstable Diode18 Unstable Gunmetal |
| 5 | +4 rows | 10000 Credits50 Unstable Diode30 Unstable Gunmetal |
If you’re short on Credits, prioritize the first two upgrades. They’re the most efficient space-per-Credit buys and stop you from making painful on-the-fly discards. Once you have a regular flow of Unstable Diode and Gunmetal from runs and contracts, finish the later tiers.
How many vault expansions are there in Marathon?
Five expansions right now; that may change with future patches. Check the CyberAcme vendor in the hub or the patch notes on Steam to confirm.
How do I increase inventory space in Marathon?
Buy Expansion upgrades from CyberAcme for vault space, and grab Enhanced backpacks for run capacity (more on that below). Use armory purchases, contract rewards, and rank milestones to stack improvements without wasting Credits.
Players on Reddit and the Marathon Discord often post build lists and vendors to farm parts; Moyens I/O’s screenshots are useful for spotting exact vendor names and UI confirmations when the game updates.
How to increase backpack size in Marathon
During a timed run I once left behind a purple module because my backpack wouldn’t take it—and that loss stung more than a death.
Your backpack is the only space that matters while you’re running. The default pack is small, but you can buy better versions at the armory, earn them from contracts, or get them as character-rank rewards. Sponsored loadouts arrive with the base pack only, but you can find and equip Enhanced backpacks during a run to trigger their effects.
How do I upgrade backpack in Marathon?
Buy Enhanced backpacks from the armory, finish specific contracts, or hit rank milestones to earn them. If you run Sponsored kits, remember those kits won’t auto-include an Enhanced pack; you must equip one you’ve found or purchased.
Small habit shifts matter: sell duplicate trash regularly, stash crafting parts you’ll actually use, and keep a mental list of items you’ll sell after a run. Treat your inventory like a ledger—if it’s profitable to keep, keep it; if not, let it go.
Carrying loot without space feels like folding a suitcase into itself: awkward and inefficient. Play the economy of runs: buy the early vault expansions, grab backpacks as you see them, and farm parts on predictable contracts so upgrades never stop costing you options.
If you had to choose one upgrade first—vault expansion or a backpack—what would you buy right now, and why?