What is standard method of drill and annular ring size of a PTH pin? In other words, how much dimension we have to add to a PTH pin to define a drill and annular ring size? According to one source we have to add 10 mils to the pin size to define drill size and have to add 25 mils to the drill size to define annular ring. Is it correct? Any reply will be appreciated.
There may well be a standard but it is probably best to talk to your fabricator on this.
The PCB tool is going to be specifying the finshed hole size, the fabricator will be using a larger drill than this to account for plating and machine tolerance, that will have an impact on how large the pad needs to be to remain attached to the board and still a complete shape, that is, not drilled through the edge.
Many fabricators who offer a prototype service will post their "no adder" rules on their web sites, these might be a good starting point if you don't have a specific fabricator in mind.
Within reason, larger is always better.
In reply to oldmouldy:
There is a rule of thumb. If nothing else is specified, the pad diameter should be at least 1.5x or 2x of diameter of the hole.
I've found this to be a helpful reference: