Bathroom sinks should be around five to eight inches deep. This will ensure that most users can easily reach their hands into the basin and comfortably wash their faces or shave.
A deeper sink can also help prevent splashing and provide more space for large items like shampoo bottles or razors.
The ideal depth for a bathroom sink largely depends on individual needs and preferences, but 5 to 8 inches is a good place to determine what size will work best for you.
The ideal depth will depend on several factors, including the height and build of the user, as well as their personal preferences.