An item sorter is the build that changes a base permanently. Not because it is clever – the circuit is four blocks deep – but because once it works, putting things away stops being a task. You throw an inventory into a chest and walk off.
It is also the most commonly half-understood redstone build in the game. Most people copy a design, it works, and the first time it jams they have no idea why.
What the circuit is actually doing
A hopper pulls items from above and pushes them sideways into a chest. A comparator reads how full that hopper is. The whole sorter rests on one trick: making the comparator output a signal only when the correct item arrives.
The method is to pre-fill the filter hopper with items you want it to catch, arranged so that one more of that item tips the comparator over the threshold. Anything else passes through.
If comparators reading containers is unfamiliar territory, signal strength and what comparators do is the piece underneath all of this.
The standard filter
The common design puts 18 filler items and 1 of the target item in the filter hopper, locked so nothing moves. Arranged across the five slots, that sits the comparator one item below the signal level you need.
- Slots 1 to 4: filler items, usually a stack-of-one item like a name tag or a renamed stick.
- Slot 5: the item you are sorting for, several of them.
- A comparator behind the hopper, feeding a redstone torch.
- The torch locks a second hopper so the filter cannot empty itself.
The hopper-locking is the part people skip and the reason sorters jam. An unlocked filter hopper slowly drains its own filter items into the chest, and a few hours later every item in the base is going to the wrong place.
Choosing filler items
The filler has to be something that never enters the system by accident. If you sort for cobblestone and use dirt as filler, one stray dirt block breaks that filter.
Renamed items are the safe answer – a stick renamed at an anvil will never arrive from a farm or a mining trip. Name tags work too and are more expensive.
Laying it out
Every sorter is the same module repeated: input hopper line along the top, one filter per item type hanging beneath it, chest under each filter, overflow at the end.
- Run a double line of hoppers along the top pointing one direction.
- Under it, place one filter module per item you want sorted.
- Each filter drops into its own chest or double chest.
- At the far end, an overflow chest catches everything unsorted.
- Feed the whole thing from one drop-off chest at the start.
The overflow chest is not optional. Without it, unsorted items back up the hopper line until the whole sorter stops, and diagnosing that from the input end is unpleasant.
What it costs
Roughly five hoppers per item type, which is 25 iron ingots, plus chests and a comparator. A twenty-item sorter is around 500 iron.
That is the real barrier, and it is why an iron farm and an item sorter tend to get built in that order. How golem spawning works covers the farm that pays for this.
Where it goes wrong
- Filter hopper not locked – the filter drains and everything mis-sorts. The most common failure by far.
- Items that stack to 16 or 1 – ender pearls, eggs, snowballs, buckets. The standard filter counts assume stacks of 64 and need adjusting.
- No overflow – the line backs up and the sorter silently stops.
- Chest full – same effect, and it looks identical to a circuit fault.
- Shulker boxes in the input – they do not stack, and they will clog a hopper line fast.
When a sorter misbehaves, check in that order. Four of those five are logistics rather than redstone, which is true of most redstone problems.
What not to sort
Not everything deserves a filter. Items you get in enormous quantity and rarely need – cobblestone, dirt, rotten flesh – are better sent to a bulk chest or a void, and items you get rarely do not justify 25 iron.
The useful list is the middle: ores, ingots, food, redstone components, building blocks you actually build with. Twenty filters covers a survival world comfortably.
Hiding it
A wall of hoppers and chests is not a room you want to look at. The standard approach is to put the mechanism behind the storage wall – barrels or chest fronts facing the room, hoppers in a service corridor behind.
Leave access. Every sorter eventually needs a filter adjusted, and one sealed inside a wall has to be demolished to fix. The layout question is covered further in storage room design.
Is it worth building?
If you mine regularly and empty a full inventory several times a session – yes, easily, and you will wonder why you waited. If you mostly build in creative-adjacent fashion or play in short sessions, the 500 iron is better spent elsewhere.
It is one of the few builds where the payoff is measured in attention rather than in resources: the thing it gives back is not having to decide where anything goes.
Images: Spelunkery project gallery on Modrinth.