How to determine the bore on interior and exterior doors
Interior doors normally have only 1 hole for a knob or lever. The ability to lock the door is determined by the door hardware function such as a privacy or passage knob or lever.
The exterior doors usually are locked with a deadbolt and are paired with a passage knob or lever. So exterior doors are usually ordered with a double bore and interior doors are usually ordered with a single bore.
The industry standard is 2 3/8″ hole for the standard door hardware on the market today. The backset is also standard at 2 5/8″.
There are no holes, hinge prep, or any prep at all on door slabs ordered without prehanging. These preparations must be done on site and will take carpentry skill and experience. There is no industry standard for the exact positioning of hinges and bore o doors. This is why retrofitting takes experience and carpentry tools. It is also easier to have the old door for taking the exact measurements
Pocket doors do not come prepped and will have to be prepped on site if you are retrofitting into an existing opening or using existing hardware. .