Outside calipers are used to measure the external size of an
object.
The same observations and technique apply to this type of caliper,
as for the Inside caliper. With some understanding of their
limitations and usage these instruments can provide a high degree
of accuracy and repeatability. They are especially useful when
measuring over very large distances, consider if the calipers are
used to measure a large diameter pipe. A vernier caliper does not
have the depth capacity to straddle this large diameter while at
the same time reach the outermost points of the pipes diameter.