Calipers are wonderful measuring tools, quick and easy to use and because the measurement is taken by contact, inherently more accurate than a rule or tape measure.

Whether you choose a traditional vernier scale (cheapest), analogue dial caliper (most accurate) or digital caliper (easiest to read), the actual measuring is performed by contact between surfaces rather than observation, which eliminates the most significant potential source of inaccuracy.

Calipers can take external, internal and depth measurements. Vernier calipers are accurate to a tenth of a mm while dial and digital calipers have a resolution of one or two hundredths of a mm.