weight going from 7mm wetsuit to drysuit?

[BFRedrocks]

Although obviously there are more details and individual testing necessary, as most folks above have already pointed out, but what I can tell you is that for me, when I switched from a 7mm wetsuit to my DUI drysuit with 250 gm thinsulate undergarment, I used the same amount of weight. So as someone else said, that's a good starting place, but you'll have to adjust it for various things like the thickness and desired "loft" of your undergarment.

As for the course, while certainly you can learn through experience and on your own, even keeping it "safe" in 15 ft of water, all it will take is that first time you inadvertently allow the air in your suit to get into your feet for you to realize that taking the class may not be such a bad idea.

 

[spoolin01]

I add about 8 lbs when switching from 7mm fullsuit wet to 7mm uncompressed neoprene dry, same profiles, typically 60 ft or less. I also stay quite a bit warmer, not even in the same ballpark, so do you call that a drysuit needing more weight, or just equivalent weight for equivalent (bouyant) insulation? Based on a handful of shell suit dives now, if the shell suit requires less weight for the same comfy dive, it won't be by much.

 

[JBFG]

I needed to add 3 lbs from my 7mm to my drysuit with my thickest (white MK2) undergarments.

I also dive a BPW.