Tried searching for this but couldn't find anything. Is there generally a formula that can ESTIMATE the interior floor space of a yacht given its exterior size? Thank you very much all.

That would have to be a very complicated and fairly useless formula. Unlike cargo vessels interiors of yachts are broken up in all sorts of ways, and also depend on the style (express, FBMY, SF,etc.). For instance you'll find many 50' sport cruisers with a 3rd stateroom that isn't much more than a closet. On certain yachts I've also notice undersizing to make the boat appear larger, i.e. undersized furniture, sinks, counters, etc. If you're thinking in terms of furnishing you'll have to go room by room on the particular yacht to get useful numbers from what I know.

I agree with NYCAP, there are so many differences from yacht to yacht on how the machinery space is laid out, which takes up interior volume. Also the design of the yacht, the beam, the height of the superstructure varies so greatly.

alright lets ignore the formula for a moment. is there a good estimate for floor space usually? e.g. how much floor space would a 60' be expected to have?

Anyone who s ever been on a boat can figure out that this question makes no sense whatsoever!!! The first factor will be the shape of the boat and how "sleek" it is. Take an older Viking or Hatteras MY. The Viking has a much shorter bow and a house that extends a lot further than most Hatteras, resulting in more interior square footage Some if the newer eurostyle boats waste even more space...

No. What everyone is trying to politely tell you is no. There are too many variables from boat to boat to even get a close guess.

No. A 60 Sunseeker Predator has fixed seating and that's all there's room for. I'm currently looking at older 56 Hats that has plenty of room for a full sofa and a couple of lounge chairs plus tables. Every boat is different. BTW, I'm sure AMG was pulling your leg. L x B = someone's chair being in the ocean next to the bow.