|This article is about an older version of DF.|
Z-Level describes vertical space (depth or altitude) within Dwarf Fortress, analogous to the Z-axis in geometry which extends out of the page towards the viewer. Each layer of view is a discrete z-level with a value relative to the bottom of the map space, indicated in the lower right corner of the screen. The player moves their view from one z-level to another by using to move up and to move down.
The default settings produce levels with around 50 z-levels of land (for an embark with average elevation changes) with an additional 15 z-levels of empty sky space above the highest point of land; mountainous regions can end up with well over a hundred z-levels of caverns.
Numerous factors available in world generation impact the available z-levels, and can alter the depth of the map to a minimum of 6 and a maximum well in excess of 600. (Worldgen has 400 z-levels; maybe one can force 200 levels of sky.)
Reducing the number of z-levels, especially cavern levels, can reduce processor demand and boost framerate.
There is another Z-level display in the upper right corner of the main view. This displays the player z-level viewpoint relative to the surface z-level.