Method 1: Crafting Table
Place 3 Andesite in a Crafting Table to make 6 Andesite Slabs.
6 How to Make an Andesite Slab in Minecraft
Use this simple recipe to make an Andesite Slab in Minecraft. You can see the exact ingredients, recipe layout, and workstation below.
Andesite Slab recipe
Follow the recipe below. The pattern must use the correct slots when the recipe is shaped.
6 
Method 2: Stonecutter
Use 1 Andesite in a Stonecutter to make 2 Andesite Slabs.
2 About this Minecraft recipe
This page shows the vanilla recipe for Andesite Slab. It includes the exact ingredients, recipe layout, required workstation, and amount produced.
The data comes from Minecraft Java 26.2. Recipes can change in later game versions, so check the version you play before crafting.