Iron Blight Backpack Upgrades: Medium and Large Locations

Iron Blight has two route-critical backpack upgrades: take the Medium Backpack in St. Toma Dormitory after the TOZ-34 and before the Hammer, then take the Large Backpack in Prasnova with the Workshop Alley Key. Pick up each upgrade before spending space on optional ammunition or another long gun, then reopen the grid and reorganize before continuing. The upgrades reduce pressure; they do not make every weapon, magazine, healing item, and key fit at once.

Backpack upgrade route at a glance

The Medium Backpack is the early upgrade that prepares you for the Hammer, Bolt Cutter, gate key, and Car Battery chain. The Large Backpack arrives immediately before the Workshop sequence begins adding the Punch Card, Blowtorch, repair parts, and nearby attachments. That timing matters more than a raw capacity number, so this guide uses route landmarks rather than inventing untested slot totals.

Upgrade	Route landmark	Take it before	Immediate priority
Medium Backpack	St. Toma Dormitory, after the TOZ-34 and before the Hammer / TT-33 Laser Sight section.	Bolt Cutter, gate key, and Car Battery.	Make room for long tools and one ready weapon.
Large Backpack	Prasnova, alongside the Workshop Alley Key.	Punch Card, Blowtorch, Pump Gauge, Drive Belt, and Jerry Can.	Keep the key and reserve space for at least two tools.

1. Find the Medium Backpack in St. Toma

The Medium Backpack appears in the St. Toma Dormitory route after the TOZ-34 and before the Hammer with the TT-33 Laser Sight. It is not a side collectible to postpone until the building is clear: the next main objectives add bulky tools and the Car Battery to the same limited grid. If you must choose between the backpack and loose optional ammunition, take the upgrade first and return only when the route is safe.

Use the St. Toma Dormitory walkthrough for the room sequence, not a video time alone. A complete route records the pickup at roughly 16:43, but that timestamp comes from an optimized run and is only a useful checkpoint. The correct landmarks—after the shotgun and before the Hammer / Laser Sight portion—remain more useful in a first playthrough.

Repack immediately after the Medium Backpack

Open the inventory in a defensible room and decide what the added space is for before filling it. Put the largest long weapon along an outer edge, keep matching magazines beside the firearm you actually use, and cluster small healing or food items together. Leave a flexible strip for the Hammer, Bolt Cutter, key, and Car Battery rather than using every new cell for shells or an extra rifle.

The best first refit is usually one ready primary weapon, a compact fallback only if its ammunition is available, one healing option, and the current route tool. Store duplicate weapons, spare ammunition for guns you are not carrying, and attachments whose compatible weapon is not in the active loadout. A bigger backpack lets you make safer choices; it is not a reason to turn every pickup into permanent baggage.

2. Find the Large Backpack in Prasnova

The Large Backpack is found with the Workshop Alley Key in Prasnova. This happens after the Connector Key portion of the route and before the Workshop adds the Punch Card, Blowtorch, Pump Gauge, Drive Belt, and Jerry Can. Take or equip the backpack and retain the Workshop Alley Key before deciding which nearby gun, laser sight, or extended magazine is worth carrying.

The complete route records the Large Backpack and Workshop Alley Key together at about 1:46:16, shortly before the OTs-20 Gnom Laser Sight and PP-91 Kedr Extended Mag. Treat that order as route evidence, not a promise about your playtime or proof that every optional pickup must be collected. The Prasnova route and Workshop guide explain the required chain around it.

Repack for the Workshop and late repair chain

The Large Backpack is most valuable when it prevents a required item from being dropped during the dense Workshop stretch. Enter with the Workshop Alley Key, one prepared weapon, compatible ammunition, one compact heal, and at least two tool-sized areas of usable space. Do not fill those areas with attachments just because the new grid looks generous.

After the Punch Card, keep the Blowtorch even when the first nearby barrier does not accept it. The route then moves into the late repair chain of Pump Gauge, Drive Belt, and Jerry Can, all of which outrank an optional firearm or loose ammunition. Use the boat repair guide once the late objective begins so you do not turn the larger inventory into a longer backtracking trip.

How to verify that an upgrade applied

After picking up a new backpack, reopen the inventory and compare the usable grid with the state before the pickup. Check the outline and placement room, not just whether your currently carried items moved; a changed arrangement can make space look lost when a long item simply no longer fits in the same orientation. Do not publish or rely on a specific total capacity unless it has been directly retested on the current build.

Patch 1.03 changed backpack behavior so players can only pick up a backpack that provides an upgrade. That is evidence of duplicate-pickup protection, not proof that every reported inventory problem has the same cause. If a first-time pickup appears not to add usable room, preserve a save from before it, record the exact backpack and area, and avoid continuing through a one-way route until you can compare the state safely.

If the backpack does not appear to work

First make sure it was a new upgrade rather than a duplicate or a pickup whose placement changed the visual layout. Confirm that Steam is current, save the inventory state, restart only after the save is protected, and compare the grid again without moving every item at once. A controlled comparison is more useful than repeatedly picking up, dropping, and reloading items while the original evidence disappears.

If the capacity still looks unchanged, capture the inventory before and after, the map area, the backpack name, and your installed build. The known-issues guide gives a report checklist and explains why a community post is not enough to declare every copy of the game bugged. Do not discard a key item just to keep testing; report the reproducible state with the save intact.

Use both upgrades to reduce backtracking, not to hoard

The Medium Backpack should make the end of St. Toma less punishing, while the Large Backpack should make the Workshop and late repair route manageable. In both cases, decide which optional items you will leave for a planned return instead of collecting everything immediately. The safest inventory is the one that can carry the next required tool, heal through one mistake, and still let you reload the weapon you are holding.

For a story-first route, take each backpack, preserve the current objective item, and defer nonessential weapons and attachments. For a collection route, create a separate save before the optional detour and do not overwrite the story-safe checkpoint. This approach gives you more value from each upgrade than chasing an unverified “perfect” inventory layout.

Verification and source limits

The route order and surrounding landmarks were checked against a completed route reference, while Patch 1.03 and Patch 1.04 provide the current behavior context as of September 13, 2026. Official material confirms the game’s limited grid, manual weapon handling, and resource pressure; it does not publish a canonical backpack-capacity table. If your pickup position or usable grid differs on a current build, report the version and evidence so the route can be retested rather than copying a stale video claim.