As a rule, your fire pit should be at least six inches below ground level, but you can certainly go deeper if you want to build a larger fire pit.
In learning how to build a fire pit on the ground, you also need to know how deep the hole for your in-ground fire pit is.
Avoid digging a fire pit hole deeper than 18 - 24” since a fire too far underground will not allow enough oxygen to help the fire bur