How to Use Vernier Caliper Depth UK: A Step-by-Step Guide

To use a vernier caliper's depth function, close the jaws, sit the end of the beam flat across the hole, and slide the depth rod down until it touches the bottom, then read the scale as normal. This UK guide covers depth, step, external and internal measuring, plus zeroing, locking and simple care.

The four ways a caliper measures

One caliper does four jobs. The large lower jaws take external sizes, the small upper jaws take internal diameters, the thin rod that slides out of the end measures depth, and the flat step at the end of the beam measures a shoulder or step. Knowing which feature to use is half of measuring well.

How to use the depth rod, step by step

1. Wipe the jaws and depth rod, then close and zero-check the caliper.
2. Sit the flat end of the beam squarely across the top of the hole.
3. Slide the depth rod down until it just touches the bottom, with light pressure.
4. Keep the beam flat so it does not rock — rocking gives a short reading.
5. Lock the screw, then read the main and vernier scales as usual.

Measuring steps and shoulders

For a step or shoulder, use the flat face at the end of the beam: rest the fixed part on the upper surface and slide the moving jaw so the step face drops to the lower one. Keep everything square and take the reading with the lock on — the same 0.02 mm scale gives you the height of the step.

External and internal jaws

For an outside diameter, close the lower jaws gently onto the part with light, even pressure. For an inside diameter, open the upper jaws inside the bore, keep them square, and note the reading. In both cases the thumb-wheel fine adjustment helps you settle onto the size without springing the jaws.

Zeroing, locking and caring for your caliper

Always zero-check first: shut the jaws and confirm the zeros line up. Use the locking screw to hold a reading, wipe the jaws after use and store the caliper dry to protect the stainless faces. Being mechanical, it needs no battery — it is ready whenever you are. If you are still learning the scales, read our how to read a vernier caliper guide first.

Frequently Asked Questions

How do you measure depth with a vernier caliper?

Sit the flat end of the beam across the opening, slide the depth rod down until it lightly touches the bottom, keep the beam flat, lock the screw, and read the scales as normal.

What is the depth rod on a caliper for?

It is the thin rod that extends from the end of the beam to measure how deep a hole, bore or recess is. It reads on the same scale as the jaws, so depth is measured to the same 0.02 mm resolution.

How do I keep a vernier caliper accurate?

Zero-check before use, avoid over-tightening the jaws, wipe the measuring faces clean, and store it dry. Handle the depth rod gently and it will hold its accuracy for years — there is no battery to fail.

Shop the Ruziza Metal 150mm stainless-steel vernier caliper — 0.02 mm resolution, ±0.03 mm accuracy, hardened stainless steel, £392.76 inc VAT, with free UK delivery, 30-day returns and a 12-month warranty.