Bore gauges with dial indicators are inserted into holes and openings to take direct measurements of bore diameters. The dial indicator is mounted to the gauge handle and the user rocks the gauge in the bore or hole to find the minimum reading on the dial.

Digital bore gauges are inserted into holes and openings to measure bore sizes. They have a digital display in the form of an integrated LCD or removable and exchangeable digital indicator that provides quick and easy reading of inside-diameter measurements of holes and openings. Gauges with 2-point contacts have interchangeable anvils and are used for a broad range of diameters. Gauges with 3-point contacts are used for a limited diameter range with the advantaging of self-centering over the arc of the contacts.

Bore gauges take indirect diameter measurements. The gauge is manually actuated and, when paired with a separately purchased digital indicator, provides a high-accuracy reading. Bore gauges without indicators are rated for accuracy and repeatability referencing the mechanical contacts of the bore gauge. Some bore gauges will be compatible with high-resolution indicators, while less expensive models may only be compatible with lower-resolution indicators.

These bore gauges do not come with an indicator, so machinists can use them with a compatible digital indicator of their choice. Bore gauges are inserted into holes and openings to measure bore diameters or other inside measurements. The user rocks the gauge in the bore to find the minimum reading on the indicator LCD, which is found when the anvils or contact points are parallel, and adds that to any anvils or extensions to determine the overall diameter. Select bore gauges may be specified as compatible with both dial and digital indicators of certain graduations. Bore gauges without indicators are rated for accuracy and repeatability referencing the mechanical contacts of the bore gauge. Some bore gauges will be compatible with high-resolution indicators with 0.0001 in or 0.00005 in graduations, while less expensive models may only be compatible with lower-resolution indicators that read to 5 tenths (0.0005 in).