If you’ve spent even an hour running through Borderlands 4’s chaotic, alien wastelands, you’ve almost certainly stumbled across glowing purple Eridium shards tucked in rock crevices, dropped by tough enemies, or hidden in secret chests. Most new players hoard it for hours without any clue what to do with it, and that’s a huge waste of one of the game’s most valuable resources. We’re breaking down exactly what is eridium used for in Borderlands 4, plus pro tips to make sure you never waste a single shard on useless purchases.
What is Eridium Used for in Borderlands 4: Core Gameplay Unlocks
The first place you’ll spend Eridium is on quality of life and progression unlocks that make every part of your playthrough smoother. These are non-negotiable purchases for new players, and you should prioritize them over fancy cosmetics or rare loot until you’ve maxed them all out. The most critical core unlocks include:
- SDU (Storage Deck Upgrade) slots: These expand your inventory space for weapons, grenades, shields, and ammo. Maxing out ammo SDUs first means you’ll never run out of bullets mid-boss fight, a mistake that’s ended more Vault Hunter runs than any boss attack.
- Fast travel point unlocks: Many remote, loot-heavy areas of Pandora and the new border planets require a small Eridium fee to unlock permanent fast travel access, saving you hours of running through enemy-infested zones between missions.
- Respec tokens: If you mess up your skill point allocation or want to switch build styles mid-playthrough, you can spend a small amount of Eridium to reset all your skill points, no need to start a new character from scratch.
We recommend holding at least 500 Eridium on hand at all times for these core unlocks as you level up. It’s easy to blow all your shards on flashy items early on, only to find you can’t carry all the rare legendaries you start finding at level 30.
Eridium for Weapon and Gear Upgrades
Once you’ve unlocked all your core SDUs and fast travel points, the next best use for Eridium is upgrading your favorite weapons and gear to keep up with increasing enemy difficulty. If you’re still unsure what is eridium used for in Borderlands 4 at mid-game, upgrading your gear is always a safe bet that will deliver immediate value for your playthrough. Borderlands 4’s new Anointment Forge lets you spend Eridium to re-roll anointments on legendary and unique weapons, so you can get the perfect perk for your build instead of farming the same boss 20 times for the right roll.
You can also spend Eridium to unlock gear level syncing, a new feature that lets you raise the level of a low-level legendary you love to match your current character level. This is game changing for players who find a perfect weapon early on but have to abandon it once they outlevel it. Keep in mind that the higher the level you’re syncing to, the more Eridium the process costs, so it’s best to save this for endgame gear you plan to use long term.
Another popular use is purchasing Eridium-exclusive legendary gear from Crazy Earl’s shop on Sanctuary III. Earl rotates his stock every 24 hours, and he often sells exclusive legendaries you can’t get anywhere else in the game, including shield mods that give you extra Eridium drops every time you kill an enemy. These mods are worth picking up as soon as you see them, as they can double your Eridium farming speed for the rest of your playthrough.
Endgame Eridium Uses for Max Level Characters
Once you hit the max level cap and have all the core upgrades you need, Eridium stops being a scarce resource and becomes a currency for chasing the best possible builds and rare endgame content. The most popular endgame use is buying entry to Mayhem Mode challenge runs, which give you double loot drops but increase enemy health and damage by up to 500% depending on the difficulty level. Higher Mayhem tiers have a higher Eridium entry fee, but the loot you get back is well worth the cost for endgame players.
You can also spend Eridium to unlock special raid boss fights that are only accessible with an Eridium entry fee. These raids drop the highest tier of legendary gear in the game, including class-specific mods that can double your damage output for your preferred build. We’ve found that farming these raids with a full co-op squad cuts down the Eridium cost per player significantly, since you only need one player to pay the entry fee for the whole group.
Many max level players also spend extra Eridium on loot luck boosts that last for 30 minutes, increasing your chance of finding legendary and unique gear by 30%. These boosts are especially worth it if you’re planning a long farming session for a specific weapon or mod, as they drastically cut down the time you’ll spend grinding. Just don’t use them if you only have 10 minutes to play, since you won’t get enough value out of the boost to justify the cost.
Common Eridium Mistakes to Avoid
After hundreds of hours of playtesting, we’ve seen a lot of players waste thousands of Eridium on purchases that offer no real long term value, especially early in the game. The biggest mistake new players make is spending all their Eridium on cosmetics before they’ve maxed out their SDU slots. Cool character skins are fun to show off, but they won’t help you survive a fight with a level 40 boss or carry all the rare loot you find.
Another common mistake is re-rolling anointments on low level gear before you hit the max level cap. Gear you use at level 20 will be obsolete by level 30, so there’s no point spending hundreds of Eridium to get a perfect anointment on a weapon you’ll abandon in a few hours. Wait until you have a max level legendary that fits your build before you start re-rolling perks.
You also don’t need to waste Eridium on respec tokens until you’ve spent at least 10 hours testing your current build. Many new players reset their skill points as soon as they hit a tough fight, but most of the time you can beat tough enemies by adjusting your playstyle or swapping out a weapon instead of blowing Eridium on a respec. If you really do want to switch builds, wait until you have at least 10 unspent skill points to make the cost worth it.
At the end of the day, Eridium is one of the most flexible and valuable resources in the game, and how you spend it will depend entirely on your playstyle and progression level. Whether you’re a new player just working through the main story or a max level Vault Hunter chasing the perfect build, understanding what is eridium used for in Borderlands 4 will help you get the most out of every shard you find. Don’t be afraid to splurge on a fun skin or a rare weapon every once in a while, but always make sure you’ve covered your core progression needs first to avoid frustrating gaps in your loadout.