The term surface gauge has two distinct and unrelated meanings. Vehicles often have surface gauges on their dashboards to indicate how the vehicle is performing in a variety of metrics. In manufacturing or metal work, a surface gauge — also known as a machinist's surface gauge, or scriber block — is a tool for scribing — or measuring — lines on materials. Surface gauges are measuring tools that may be used for a variety of purposes including finding the center of a cylinder and determining whether a plane's surface is truly horizontal.

Surface gauges typically have a steel base on which an adjustable vertical arm is mounted. One or two scribers are mounted on the vertical arm and can be adjusted with a coarse and a fine adjustment. In smaller size surface gauges, these adjustments may be 4 in and 7 in (about 10 cm and 18 cm) and in larger sizes, 9 in and 12 in (about 23 cm and 30). When used to mark material, scribers might scrape lines into the material, scrape off paint on the material, or in some models, the scriber can be replaced with a pencil to mark lines.

One common use of a surface gauge is to find the center of a cylinder. It can be used to find the center of an object that has a round cross-section. The object, usually a cylindrical bar, is placed in a vee holder which holds the bar horizontally. The surface gauge is then used to measure how far the top of the circle is from the bottom. The halfway point is determined and then marked. The cylinder is then turned about 90 degrees in the vee block and the process is repeated. The result is an "x" that marks the exact center of the cylindrical surface.

Perhaps the most common use of a surface gauge is determining whether the surface of an object is truly horizontal. To do this, the machinist will manually move the surface gauge across the surface of the object. The gauge will tell the machinist how far the surface of the object is from it's base with precision. If the number varies, the surface is not perfectly horizontal.

Surface gauges truly have a whole host of uses. They can also be used to compare the measurements of different parts to make sure they have precisely the same measurements. Parallel lines can also be drawn with the help of a surface gauge.

A surface gauge on a vehicle's dashboard is a plate that provides a driver with various performance indicators. This includes the MPH (Miles Per Hour) or KPH (Kilometers Per Hour) gauge that shows the vehicle’s speed, the RPM (Revolutions Per Minute) gauge that shows the engine rotations, and the gas gauge that shows how full or empty the gas tank is. Other common vehicle performance indicators include the engine heat gauge, the oil gauge, and the battery indicator.