What are the advantages and
disadvantages of dial calipers?

Advantages

No batteries required

As dial calipers use a rack and pinion mechanism, they do not require batteries. This makes them both environmentally and economically friendly.

Can be used in wet conditions

Even though they are not waterproof, dial calipers work well even when damp.

Measurements are clearly displayed

The main feature of the dial caliper, the dial, displays measurements very clearly and makes the tool much easier to read than a traditional vernier caliper.

Disadvantages

Rack and pinion 

If the caliper is dropped, the rack and pinion can become misaligned leading to inaccurate measurements. If this happens, it can be difficult to recalibrate the caliper.

Measurements are in either millimetres or inches

Most dial calipers provide the user with either imperical or metric readings, not both. Converting readings from one measurement system to another can sometimes lead to errors.