Bore Gauges

Select based on measurement range (small dial bore gauges for 0–2 in, telescoping or electronic gauges for larger bores), required accuracy (mechanical dial gauges for general use, digital for finer resolution), and the work environment (robust or sealed models for shop use)

Common mechanical dial bore gauges typically offer accuracy in the thousandths of an inch (0.001 in) with similar resolution, while digital bore gauges can offer higher resolution (0.0005 in or 0.01 mm); check specifications for repeatability and calibration data

Digital gauges provide easier readout, data output for recording, and often finer resolution, but mechanical dials can be more affordable and durable for routine shop checks; consider how important digital readout, data transfer, and resolution are for your work

Many bore gauges use interchangeable anvils or extension rods; choose a kit with probe heads that cover your smallest to largest bores or plan to buy additional heads so you can set and calibrate the gauge at the desired nominal diameter

Calibrate using a micrometer or ring gauge at the target nominal diameter: set the reference on the micrometer, insert the bore gauge, rock to find minimum reading, and adjust the dial or zero the digital readout to match the reference

Keep gauges clean and lightly oiled, store in protective cases away from moisture and impact, avoid excessive force on the measuring head, and have them periodically checked against calibrated standards to detect drift

Entry-level mechanical or telescoping bore gauges and basic kits often fall under $50, while mid-range dial and many digital kits commonly sit around tens to low hundreds of dollars; higher-precision or complete multi-head digital kits cost more