A mob grinder is not the whole farm. It is the second half: the mechanism that turns mobs your spawning platform produces into either items in a chest or XP in your bar. The general mob farm guide covers the spawning platform, the water funnel, and AFK placement. This guide covers only the grinder itself, the part at the bottom of the shaft that actually kills the mob, because that single design choice decides what your farm is for.
Tested on: Minecraft 26.2, Java Edition, vanilla survival. Fall-damage figures below are documented game mechanics, not measured rates. Your farm's item and XP output still depends on spawn volume, which the general mob farm guide covers.
The choice a grinder makes for you
Every kill method sits on one axis: automatic or player-delivered.
| Method | Gives XP | Gives drops | Needs you present | Effort |
|---|---|---|---|---|
| Fall damage to 1 HP + player hit | Yes | Yes, with Looting | Yes, at the kill spot | Low |
| Lava blade (auto-kill) | No | Yes, no Looting | No | Low |
| Campfire (auto-kill) | No | Yes, no Looting | No | Very low |
| Magma block (auto-kill) | No | Yes, no Looting | No | Very low |
| Fall damage outright (24+ blocks) | No | Yes, no Looting | No | Low |
Pros
- Auto-kill methods run with nobody home, forever, no AFK time spent
- Player-kill methods are the only source of XP and let Looting multiply drops
- Both can share the same spawning platform and funnel; only the last few blocks differ
Cons
- Auto-kill drops have no Looting bonus, so gunpowder, string, and bones come at the base rate
- Player-kill demands your attention the whole time the farm runs
- Getting the fall height wrong either kills mobs outright (auto) or leaves them too healthy to one-hit
There is no universally correct answer. If you want gunpowder and bones stacking in a chest while you build elsewhere, auto-kill. If you want levels for an enchanting table, only a player-kill shaft works, because XP-bearing mobs drop experience only when a player lands the final hit. Fall damage, lava, campfires, and suffocation all kill the mob and drop its items, but none of them award XP.
The fall-damage maths
This is the part worth getting exactly right, because a few blocks either way changes what the grinder produces.
The rule: a mob takes no fall damage for the first 3 blocks it falls, then 1 damage point (half a heart) for every block after that.
Zombies and skeletons have 20 HP (10 hearts), which is the baseline most dark-room and general-purpose grinders are built around:
- To leave a mob at 1 HP, you need to deal 19 damage.
- 19 damage beyond the free 3 blocks means a fall of 22 blocks.
- At 22-23 blocks, an unarmored zombie or skeleton lands at 1 HP: one hit from any weapon finishes it, and because a player lands that hit, you get the XP and your Looting enchant applies to the drop.
Do not push past 23 blocks if you want mobs alive. At 24 blocks and beyond, unarmored zombies and skeletons start dying from the fall itself before they reach you, which converts your XP into a wasted drop on the floor. If auto-kill by fall alone is the goal, that is a feature, not a bug: build the shaft deeper instead, 30+ blocks reliably kills outright with no lava or campfire needed.
Two wrinkles worth knowing: armored zombies and skeletons absorb some fall damage and can survive above 1 HP at 22 blocks, but they are a small minority of spawns and a Looting sword clears them in a second swing. And 22 blocks is specifically calibrated to 20 HP mobs; a platform producing anything with a different HP pool needs its own height, though for the standard dark-room or cave-spawn cast (zombies, skeletons, creepers, spiders), 22-23 blocks covers all of them.
Player-kill design: the drop shaft and kill spot
This is the design used by the general mob farm and the XP farm, and it is worth building correctly once rather than patching later.
The shaft. Exactly 1 block wide, so mobs fall cleanly without catching on a wall or ledge. If your spawning floors sit above multiple stacked levels, route their water funnels into a single vertical shaft first; mobs take no fall damage while riding water, so you can stack as many floors as you want above the shaft and only the final open-air gap at the bottom needs to measure 22-23 blocks.
The landing trench. A 1-block-wide trench or single block at the shaft's base, just wide enough for mobs to land in a line in front of you. Wider trenches let mobs spread out of your attack range.
The barrier. A half-slab, trapdoor, or fence gate between you and the trench keeps mobs from hitting you back while your sword still reaches through. Stand behind it and swing once per mob.
Hoppers underneath. Hopper minecarts or block hoppers under the trench catch drops and feed a hopper chain into storage. This is the same collection layer the general mob farm guide describes; nothing about the grinder changes it.
If you want a hands-off version of the player-kill grinder, a trapdoor over the landing spot holds mobs one at a time. Hold the attack button and each mob drops in and dies the moment it lands, letting you AFK-click instead of watching for arrivals. You are still present and the killing blow is still yours, so XP and Looting both still apply.
Auto-kill methods
If XP is not the goal, an unattended kill method removes the need for a player at all. All three below give item drops with no XP and no Looting bonus.
Lava blade. A lava source placed so only its edge (not the full block) touches the mob's path kills instantly without burning the drops, typically a lava source in a wall alcove behind a sign or carpet that exposes just the block-edge hitbox. Fast, but precise; get the placement wrong and fire spreads or drops burn.
Campfire. Placed under the shaft, it deals continuous small damage without setting drops alight, since campfires do not burn items. Slower than lava, but trivial to build and hard to get wrong.
Magma block. Damages anything standing on it, similarly to a campfire but slightly faster, and equally safe for drops. One block, no alignment needed.
<Shopping items={[{ name: "Campfire", note: "Craft from sticks, coal/charcoal, and logs; safest and simplest auto-kill floor" }, { name: "Magma block", note: "Found in ocean and Nether magma cube biomes, or crafted from 4 magma cream" }, { name: "Lava bucket", note: "For a lava blade; needs exact edge placement to avoid burning drops" }]} />
For any of these three, the shaft height barely matters since fall damage is not doing the killing. A shorter shaft (even under 22 blocks) is fine because the floor mechanism finishes the job regardless of how much HP the mob has left.
Common mistakes
Fall too short. Below 22 blocks, mobs land with too much HP for a reliable one-hit kill, slowing player-kill throughput and letting mobs pile up in the trench.
Fall too long for a player-kill build. Past 23-24 blocks, unarmored zombies and skeletons start dying outright from the fall itself. You still get drops, but zero XP, defeating the point of a player-kill shaft.
Lava blade burning the drops. A full lava block instead of an edge-only exposure destroys everything that touches it, items included. Use a campfire or magma block instead if you are not confident placing the lava correctly.
Expecting Looting on an auto-kill farm. Looting only applies to player kills. An auto-kill farm's gunpowder, string, and bone output is fixed at the base drop rate no matter what sword you are or are not holding, because you are not holding anything relevant at all.
Landing trench too wide. Mobs spread out past your attack range in a player-kill design, letting some survive multiple ticks and clutter the chamber. Keep it to 1 block wide.
Frequently asked questions
How tall does a mob grinder drop need to be?
For the standard 20 HP overworld hostiles (zombies, skeletons, creepers, spiders), 22-23 blocks brings an unarmored mob to 1 HP, low enough for a single player hit to finish it and register the kill as yours. Fall damage in Minecraft deals no damage for the first 3 blocks, then 1 damage point per block after that, so 3 plus 19 damage points equals 22 blocks.
Why does my mob grinder give drops but no XP?
The mob is dying from fall damage, lava, a campfire, or a magma block before you land a hit. XP only drops from a player-delivered killing blow. If you want XP, shorten the fall to 22-23 blocks so mobs survive to be finished off by you, and remove any auto-kill floor mechanism from that shaft.
Is a lava blade or a campfire better for an auto-kill grinder?
A campfire is simpler and safer: it damages mobs without any risk of burning the item drops, and needs no precise placement. A lava blade kills faster but only if you expose just the block's edge to the mob's path; get the placement wrong and it burns the drops along with the mob. For a first build, use a campfire or magma block.
Does Looting work on an auto-kill mob grinder?
No. Looting is an enchantment on a weapon you swing, and it only applies when you land the killing blow. Fall damage, lava, campfires, and magma blocks are all environmental kills, so drops come at the unmodified base rate regardless of your gear.
Can one grinder do both XP and auto-kill?
Not from the same fall. You can switch a shaft between a player-kill trench and an auto-kill floor with a retractable barrier, but that is an upgrade for later, not something a first build needs. Pick one method and build it well.
Related farms
For the spawning platform, water funnel, and AFK placement that feed a grinder, see the general mob farm guide. If XP output specifically is your goal, the XP farm guide ranks every XP source, including how a dark-room grinder compares to a gold farm and an enderman farm. A mob switch stops hostile spawns everywhere else so your grinder claims the full mob cap.
This guide is part of our Minecraft farm guides collection for 26.2.
Sources & further reading:
