So, you finally found one. You were digging for iron or maybe just exploring a random cave system when that mossy cobblestone appeared. Your heart skipped a beat because you knew exactly what those spinning blue flames meant. You found a dungeon. Now, you could just break the spawner, grab the loot, and leave, but that’s a rookie move. Honestly, knowing how to make a xp farm with a zombie spawner is basically a rite of passage for any Minecraft player who actually wants to enchant their gear without spending ten hours trading with villagers.
It’s surprisingly simple, yet most people overthink the mechanics.
The Physics of the Spawner
Before you start placing blocks, you have to understand how the game actually decides when a zombie spawns. Most players assume the spawner just "works." It doesn't. If you stand too far away, it turns off. If you stand too close and fill the room with torches, it shuts down. If the room is already full of zombies, it stops.
The game checks an area of 9x9x3 around the spawner block. If there are already six or more zombies in that zone, the spawner takes a break. This is why "falling" farms are so popular. You have to get the zombies out of that detection zone as fast as possible so the spawner keeps pumping them out. If they just hang around the spawner's feet, your rates are going to be absolute garbage.
Setting Up the Kill Chamber and Why It Matters
First thing’s first: light the place up. Put a torch on top of the spawner and on the walls. You don't want a zombie chewing on your back while you're trying to measure the room.
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Clear out a space that is 4 blocks away from the spawner in every horizontal direction. This gives you that 9x9 room. Then, dig down 3 blocks from the floor of the spawner and clear out 2 blocks above it. You need a big, hollow cube. If you skip this part and leave the room small, the zombies won't have enough space to spawn efficiently. Efficiency is the name of the game here.
Once the room is cleared, you need to move them. Water is your best friend.
Moving the Horde
Place two water buckets in the corners of one side of the room. The water should flow toward the opposite wall, but it won't reach all the way. You'll need to dig out the last row of blocks where the water stops so the flow continues into a trench. This trench should lead to a single hole.
This is where things get a bit technical, but don't sweat it. You've basically created a funnel.
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Now, you have a choice. You can either kill them right there at the bottom of a hole, or you can use a bubble column to lift them up so they can fall and take damage. If they take fall damage first, you only have to hit them once with your hand or a wooden sword to get that sweet, sweet XP. To make a bubble column, you need soul sand. Put the soul sand at the bottom of a vertical shaft, fill the shaft with water source blocks (kelp is the easiest way to turn flowing water into source blocks), and watch the zombies zip upward like they're on a very damp elevator.
The Problem with Baby Zombies
Let's talk about the literal worst thing in Minecraft: baby zombies. They are fast. They fit through 1x1 gaps. They will ruin your life.
When you're designing the "killing window" where you stand to hit the zombies, make sure you use a slab. If you leave a full block gap, the babies will squeeze through and start hacking at your shins. Most experienced players like Pixlriffs or the guys on the Hermitcraft server recommend using a "filter" or just a very tight slab configuration. Honestly, I just use a trapdoor or a slab at eye level. It keeps them contained while I swing away.
Boosting Your Rates with Better Mechanics
If you want to get fancy, you can incorporate a looting III sword. It doesn't just give you more rotten flesh; it actually feels like it helps the XP flow better, though technically XP drops are fixed.
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One thing people often forget is the "player proximity" rule. You have to be within 16 blocks of the spawner for it to be active. If your killing chamber is 20 blocks away, nothing will happen. You’ll be sitting there staring at an empty hole like a dummy. Always make sure your AFK spot or killing floor is close enough to keep those little blue flames inside the spawner spinning.
Why Zombies are Better Than Skeletons (Sometimes)
I know, I know. Skeletons give you bones and arrows. They're objectively "better" loot. But zombies have a secret weapon for your farm: reinforcements.
In Hard mode, zombies have a chance to spawn "reinforcements" when they take damage. Sometimes, a zombie spawner farm can actually get a slight boost in numbers because of this mechanic. Plus, if you leave a zombie in water long enough, it turns into a Drowned. While Drowned farms are usually better built in the ocean, a zombie spawner can technically be converted into a Drowned farm if you want those copper drops or the occasional nautilus shell. Just remember that once they convert, they regain their health, so your "one-hit kill" fall damage setup might not work as well.
Dealing with the Loot Overflow
You are going to get a lot of rotten flesh. Like, a stupid amount.
Don't just throw it away. If you’ve got a Cleric villager nearby, rotten flesh is basically free emeralds. Build a few chests with hoppers underneath your killing floor. This way, while you’re standing there clicking away, the items are automatically sorted. It keeps your inventory clean and ensures you don't lose any rare drops like iron ingots, carrots, or those random gold shovels zombies love to carry.
Actionable Next Steps for Your Farm
- Clear the 9x9x5 Area: Ensure the spawner is dead center to maximize the spawn attempts per cycle.
- Water Flow Logic: Use a trench system to funnel all zombies into a 1x1 hole.
- The Bubble Lift: Place Soul Sand at the bottom of a water column and use Kelp to create source blocks all the way up to the top.
- Drop Height: Drop the zombies exactly 21.5 blocks. This leaves them with half a heart of health, making them a "one-tap" kill.
- Slabs and Safety: Use bottom-half slabs in your killing window to prevent baby zombies from escaping and ending your hardcore run.
- Light Check: Once the build is done, remove the torches. If it's not dark, they won't spawn. It sounds obvious, but we've all forgotten it at least once.