How to Read a Standard Slide Vernier Caliper

Slide vernier calipers are typically used to measure objects which cannot be measured using a standard ruler or tape measure. It is also used when an additional digit of accuracy is desired, which a standard ruler can not provide. Learning to read a slide vernier caliper takes practice, since it must be read differently than a ruler or tape measure.

Slide calipers are used for measurements in which rulers do not suffice.
  1. Place the object between the tips of the vernier caliper. Slide the caliper tips or jaws until they squeeze the object being measured. Do not apply too much pressure, as it could damage the object or produce an inaccurate measurement. Some vernier calipers are adjusted by rotating knobs, while others can be slid into place.

  2. Read the alignment of the zero on the millimeter or centimeter scale with the measurement ticks displayed on the center. A millimeter slide will appear above the measurement ticks, while the centimeter slide is displayed below.

  3. Find the third significant digit. If the zero does not align precisely with one of the measurement ticks, a third digit should be determined. An example is when the zero mark is between 2.5 and 2.6 millimeters. To determine the third figure in the measurement, look to the right of the zero. A whole number will line up with a measurement tick on the scale. The measurement ticks compose the center of the scale.

  4. Measure the length, width and height of the object to determine volume. Vernier calipers can also be used to determine the diameter of circular objects.

  5. Record each measurement on a piece of paper or notebook. Always write an answer out to the third digit, such as 2.32 centimeters.


  • Vernier caliper tips can be sharp. Use caution during measurement to avoid injury.