accounting for trub in boil volume

I was running some numbers for my first AG through "Nelsons Beer Quick calculator" (pretty cool program!) and it has a boil number and a batch number.(in gallons) When putting the data in for a 5 gallon batch, should I go with 6 and 5 gallons(boil and batch)based on 60 min boil with 1 gallon evap, or 6.25/5.25 to account for the trub in order to end with a true 5 gallons in the fermenter. I'm planning a biab with a dunk sparge in a separate pot of strike water, and a full volume boil. I'm also looking at 1/1.25 grain to water. should I bump this up a bit 1/1.5 or more. I could probably do a full volume mash, but I like the idea of a little sparge to bump my efficiency a bit. Any advice would be greatly appreciated!

One thing you might consider, is the hops. Whole hops will soak up a considerable amount of wort. I usually error on the high end, around 1.25 to 1.5 to grain. Pellets on the other hand, hardly soak anything. Happy brewing!

I'm using pellet, so I should be good there. I figured I'd try Edwort's "Haus ale" for my first AG. Seems a lot of people like this, and have had good results. Plus it's a smallish grain bill with one kind of hops throughout so I can concentrate on my process, and less on keeping multiple different additions straight in my head.

yeaaa whole hops soak up a LOT!

I got a little over 4 gallons using lose hops for a 5gal recipe.