The pocket door hardware manufacturer may have door size recommendations.

A 30" Inch pocket door goes into a 60 inch plus one inch rough in/ opening. Why the arch??! unless it is opening to something quite special? The arch is the high point....84 of your door?

You may want to create a template : )

You watched too much Instagram?

A bit of overkill in my book : ) but you may have a different concept

Jan - Maybe too much instagram, maybe too much having grown up money and the desire to waste it on things I think are aesthetically pleasing. Either way, very much appreciate the replies here. Very helpful!

A 30” door is used and yes the opening ends up slightly less than 30”. For a real shock measure the opening for a hinged door- with the door at 90° you lose 1 1/2”.

Custom they always use a wider door stile on the side that goes in the pocket to help hide the gap when the door is closed. But using stock doors just wider will make the balance of the door look odd in the opening if you go wider overall.

Who is doing the install? That is who you ask and I have no clue about the arched opening is odd and whay pocket door there at all. We need context and you need to get a good installer .

Skip the arch. You are likely to end up with some pp mongrelized atrocity from your average carpenter. It takes some higher end skills to make that look like anything, and actually work.