A height gauge/height gage is a measuring device to determine the height of objects and to mark items to be worked on. It is used in metalworking or metrology to set or measure vertical distances; the pointer is sharpened to act as a scriber and assist in marking out workpieces.
A height gauge may also be used to measure the height of an object by using the underside of the scriber as the datum. The datum may be permanently fixed or the height gauge may have provision to adjust the scale, this is done by sliding the scale vertically along the body of the height gauge by turning a fine feed screw at the top of the gauge; then with the scriber set to the same level as the base, the scale can be matched to it. That adjustment allows different scribers or probes to be used, as well as adjusting for any errors in a damaged or resharpened probe.
In the toolroom or a machine shop, the difference between a height gauge and a surface gauge is that the height gauge has a measuring head (whether vernier, fine rack and pinion with dial or linear encoder with digital display), whereas the surface gauge has only a scriber point. Both are typically used on a surface plate and have a heavy base with an accurately flat, smooth underside.