How to Make a Cobblestone Generator in Minecraft
Build an unlimited cobblestone generator in minutes. This guide covers basic, automatic, and skyblock designs — plus how to avoid the obsidian mistake everyone makes.
Table of Contents
What Is a Cobblestone Generator?
A cobblestone generator is a simple Minecraft machine that produces unlimited cobblestone blocks. It works by making water and lava flow together — when they meet, the lava turns into cobblestone. You mine the cobblestone, and a new block forms instantly.
Cobblestone generators are essential in skyblock, where resources are limited, but they're useful in any survival world. Cobblestone is one of the most important building materials, used for walls, paths, furnaces, stone tools, and brewing stands.
Once you have unlimited cobblestone, you can use our circle generator to plan circular walls and structures, or our sphere generator for dome designs — all built with free cobblestone from your generator.
Basic Cobblestone Generator (Step by Step)
This is the simplest design that works in both Java Edition and Bedrock Edition. You only need one water bucket and one lava bucket.
1Dig the Trench
Dig a 1-block wide, 1-block deep trench that is 4 blocks long.
2Create Water Channel
At one end of the trench, dig an extra block. Place water in this end block. The water flows toward the middle.
3Add Lava
At the opposite end, place your lava bucket. The lava flows toward the water.
4Mine Cobblestone
Where water and lava meet, cobblestone forms. Mine it and a new block appears instantly. Repeat forever!
Important: The trench must be exactly the right length so water and lava meet in the middle. If the trench is too short, you get obsidian. If it's too long, they won't meet at all. A 4-block trench is the standard size.
Common Mistakes to Avoid
Getting obsidian instead of cobblestone
Fix: Water is flowing ON TOP of lava. Redesign so they meet at the same level, flowing toward each other.
Lava source disappearing
Fix: You accidentally let water flow into the lava source block. Always place lava last, and make sure the water doesn't reach the lava source.
Water flooding everywhere
Fix: Your trench isn't contained. Build walls around the water channel to control the flow direction.
Can't mine cobblestone fast enough
Fix: Use an iron or diamond pickaxe for faster mining. Or upgrade to an automatic piston-based design.
Automatic Cobblestone Generator
An automatic cobblestone generator uses pistons and redstone to push cobblestone out of the way as it forms. This lets you mine continuously without repositioning.
Piston-Based Design
- Build the basic cobblestone generator first
- Place a piston facing the cobblestone formation point
- Connect a redstone clock (repeater loop) to the piston
- The piston pushes cobblestone forward each time a new block forms
- Mine the pushed row of cobblestone at the end
For more redstone ideas, check our redstone circular builds guide which covers redstone clocks and piston mechanics in detail.
Skyblock Cobblestone Generator
In skyblock, your cobblestone generator is your lifeline. You start with limited lava and water, so building it correctly the first time is critical.
Stone Generator Variant
Want smooth stone instead of cobblestone? A stone generator works differently: lava must flow on top of still water. This creates smooth stone directly, saving you the coal and time needed to smelt cobblestone into stone.
- Dig a 1-block deep hole and fill it with water (source block, not flowing)
- Place a block above the water with a 1-block gap
- Place lava on top so it flows down onto the water surface
- The lava touching the water creates smooth stone
- Mine the stone with a silk touch pickaxe for smooth stone blocks
Advanced Designs & AFK Farms
For serious builders who need massive amounts of cobblestone:
TNT Duper Farm
Uses TNT duplication glitch to blast cobblestone. Hoppers collect the drops. Produces 10,000+ blocks per hour. Works in Java Edition.
Wither Farm
The Wither boss destroys cobblestone as it forms. Combined with hoppers, this creates an industrial-scale farm. Advanced build requiring game knowledge.
Multi-Layer Generator
Stack multiple cobblestone generators vertically. Mine all layers at once for 3-5x faster production. Simple to build, very effective.
Piston Conveyor
Pistons push cobblestone along a conveyor belt into a collection area. Semi-automatic — you just hold down the mine button.
All that cobblestone is perfect for building massive structures. Plan your build with our circle generator for round walls or our survival base guide for complete base layouts.
Related Minecraft Generator Guides
Frequently Asked Questions
How do you make a cobblestone generator in Minecraft?
Dig a 1x4 trench, place water at one end and lava at the other. The water and lava meet in the middle to create cobblestone. Mine the cobblestone, and a new block forms instantly. This gives you unlimited cobblestone without mining underground.
Why is my cobblestone generator making obsidian instead?
Obsidian forms when water flows on top of a lava source block. To prevent this, make sure the lava is at the same level as or above the water flow. The water should flow toward the lava, not on top of it. Redesign your trench so water and lava meet at the same height.
Can you make an automatic cobblestone generator?
Yes! Use pistons and redstone to automatically push cobblestone into a collection area. Advanced designs use TNT dupers to blow up the cobblestone and hoppers to collect it. AFK cobblestone farms can produce thousands of blocks per hour.
What is the fastest cobblestone generator design?
The fastest designs use TNT dupers with blast chambers. These can produce over 10,000 cobblestone per hour. For simpler builds, a piston-based design with a redstone clock pushes cobblestone into a row for quick mining at about 1,000 blocks per hour.
Does a cobblestone generator work in Bedrock Edition?
Yes, cobblestone generators work in both Java and Bedrock Edition. The basic water-meets-lava mechanic is the same. However, some advanced redstone designs differ between editions, so check your edition before building complex automatic farms.
How do I make a cobblestone generator on a skyblock island?
In skyblock, you start with limited lava and water. Place the lava source carefully — you only get one bucket! Dig a trench with the lava at one end and water at the other. Make sure the water flows toward the lava, not over it. A common mistake is losing your only lava source to obsidian.
Can I make a stone generator instead of cobblestone?
Yes! If lava flows on top of water (instead of water flowing into lava), you get smooth stone instead of cobblestone. Stone generators are more useful because you skip the smelting step. The design is slightly different from a cobblestone generator.
Plan Your Cobblestone Builds
Got unlimited cobblestone? Plan amazing structures with our free building tools.