How to Build an Item Sorter in Minecraft
Hopper-based overflow-proof item sorter tutorial. Covers the 41-item filter, comparator mechanics, channel layout, and how to handle non-stackable items.
An item sorter automatically separates items from a mixed input stream into labeled chests. The standard design uses hoppers, comparators, and redstone torches in a compact, tileable module. Each module filters one item type. Line up as many modules as you need, and every item goes to the right chest. This guide covers the overflow-proof design that works reliably in survival.
Why build an item sorter?
- Organize mob farm output (bones, arrows, rotten flesh, armor, etc.).
- Sort mining hauls (cobblestone, iron, gold, diamonds, redstone).
- Manage crop farm output (wheat, carrots, potatoes, beetroot).
- Tileable design scales from 5 items to 100+.
How the filter works (the 41-item trick)
Each sorting module uses a hopper with a specific item arrangement:
- Slot 1: 41 of the item you want to filter.
- Slots 2-5: 1 each of a non-stackable or unique filler item (like renamed sticks).
Total: 45 items in the hopper. A comparator reads this hopper and outputs signal strength 3. When one more matching item enters the hopper (from the input stream above), the count goes to 46, and the comparator output increases to signal strength 4. This stronger signal powers a redstone torch below, unlocking a lower hopper that pulls the extra item into the output chest.
The filler items in slots 2-5 prevent unwanted items from entering those slots (since they are non-stackable or renamed, no other item can stack with them). Only the target item can enter slot 1, triggering the filter.
Materials per sorting module
| Item | Quantity |
|---|---|
| Hoppers | 3 |
| Comparator | 1 |
| Redstone torch | 1 |
| Redstone dust | 2 |
| Chest (or double chest) | 1-2 |
| Building blocks | ~6 |
| Target item | 41 |
| Filler items (renamed sticks) | 4 |
Step-by-step build instructions
Step 1: Build the input line
Place a row of hoppers along the top of your sorting system. These hoppers form the input stream. Items enter at one end (from a farm, manual input chest, etc.) and flow through the hopper chain. Each hopper in the chain sits above a sorting module.
Side view of one module:
[Input hopper chain] ------> (top row, items flow left to right)
|
[Filter hopper] (contains 41 target + 4 filler)
|
[Comparator] --> [Redstone] --> [Torch on block]
|
[Output hopper] --> [Chest]Step 2: Place the filter hopper
Below the input chain, place a hopper pointing into the output system (down or sideways toward the chest). This is the filter hopper. Load it with 41 of the target item and 4 filler items (each in a separate slot).
Step 3: Add the comparator and redstone
Place a comparator reading from the filter hopper (the comparator's back faces the hopper). Run 2 blocks of redstone dust from the comparator's output to a block with a redstone torch on its side. The torch faces downward toward the output hopper.
When the filter hopper has exactly 45 items (its resting state), the comparator outputs signal strength 3, which is not strong enough to reach the torch over 2 blocks of dust. The torch stays ON, locking the output hopper (torches lock hoppers when powered into their side).
When a matching item enters (46 items), signal strength becomes 4, which reaches the torch. The torch turns OFF, unlocking the output hopper for one item transfer. After the item leaves, the count drops back to 45, the signal weakens, the torch re-locks, and the system resets.
Step 4: Place the output hopper and chest
The output hopper sits below the filter hopper, locked by the redstone torch. When unlocked, it pulls items from the filter hopper and pushes them into a chest. Place a double chest at the end of the output hopper.
Step 5: Tile the design
Place identical modules side by side along the input chain. Each module sorts one item type. At the end of the input chain, place a "catch-all" chest that collects anything the sorter did not filter. This prevents overflow.
Overflow protection
The 41-item design is inherently overflow-proof. Even if the output chest fills completely, the filter hopper holds at most 46 items temporarily (41 target + 4 filler + 1 incoming). The system simply stops pulling from the input chain when the output is full, and items continue down the input chain to the next module or catch-all.
Without the filler items, random items could fill the empty slots in the filter hopper, eventually clogging it. The filler items prevent this by occupying slots 2-5 permanently.
Handling non-stackable items
This design only works for stackable items (items that stack to 16 or 64). Non-stackable items (armor, tools, weapons, potions) cannot be sorted with the comparator method because they always have a stack size of 1. For non-stackables, use an overflow design: let them pass through all sorting modules to the catch-all chest, or use a separate system with allays (1.19+) or water stream sorting based on item despawn timing.
Common mistakes
- Wrong number of filter items. Using 40 or 42 instead of 41 changes the comparator thresholds and breaks the filter. Always use exactly 41.
- Filler items that can stack with input. If you use regular sticks as filler items and sticks enter the input stream, the filler slots fill up and the filter breaks. Use items renamed in an anvil (a renamed stick cannot stack with a normal stick).
- Comparator in wrong mode. The comparator must be in default mode (not subtract mode). If the front torch on the comparator is lit, it is in subtract mode. Right-click to toggle back.
- Hopper pointing wrong direction. The filter hopper must point into the output system. If it points the wrong way, filtered items go back into the input chain.
- No catch-all chest. Items that match no filter continue down the input chain. Without a chest at the end, they back up and clog the entire system.
Frequently asked questions
How many items can the sorter handle per second?
Each hopper transfers 1 item every 4 game ticks (0.4 seconds). A single input chain handles about 2.5 items per second. For faster throughput, run multiple input chains in parallel.
Does this work on Bedrock Edition?
Yes. The comparator and hopper mechanics are identical on Bedrock. The design works without modification.
Can I sort items that stack to 16 (like ender pearls)?
Yes, but the filter numbers change. For 16-stackable items, use 10 of the target item in slot 1 and fill slots 2-5 with filler items as usual. The comparator thresholds adjust accordingly.
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