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Ive heard people say that they use a 32 and its fine, other that they would never use anything less than a 36. What size do you use, and why?

In my opinion, it very much depends on several factors: your typical airspeed at the pull time, the way you pull (read: burble characteristics), and canopy weight. I think a good indication that PC size is adequate is if you don't have a too noticeable delay between pitch and line stretch (similar to non-wingsuit deployment).

I use non-vented F111 38" with Flik 322 (~11lbs).

I use a 38" vented large mesh PC with a FLIK 242/Multi/Vented for every wingsuit jump between 800' and Terminal.

Either you do like Yuri said and calculate on the stuff. or you go the safe way and take a bigger one.

when in doubth.. go big. its never wrong. Lower speed = Bigger PC

I use a 36... I would like to use a 38, but I cant fit it in my leg-pouch.

I can barely fit my fine mesh 36 in my V1 leg pouch.

Some examples.

Suppose you pull from full flight and your speed is 90mph horizontally and 36mph vertically (L/D = 2.5). Your total speed is therefore 97mph. Compared to a terminal non-wingsuit jump at 120mph, that's (120/97)^2 = 1.53, or 53% reduction in pull force for the same size PC. To compensate for this, you need a PC with 53% larger area, so if you use 32" for non-wingsuit terminal, you need 32*sqrt(1.53) = 40" for wingsuit. You see, 38" doesn't seem to be large anymore!

Similarly, different canopy sizes. Fox 285 weighs almost 11lbs, while Trango 225 probably around 6. So acceleration of tiny Trango to linestretch would be almost twice as violent as of large F111 canopy (imagine what it can do to your neat figure-8's in tailpocket). So it's logical to use a bit smaller PC for a very light canopy.

Haven't you missed off a squared relationship? The pull-force is proprtional to the square of the PC diameter, so sqrt[32^2*sqrt(1.53)]=36"?

[given that the force difference is the difference betwen the differentials on speed]

...if I remember my maths right?

Anyway, I'm sure we all agree that wingsuit deployments occur at lower speeds than terminal skydives

Think about it this way: area is proportional to the square of diameter, force is proportional to the square of speed, so for the same force diameter is inversely proportional to speed. Half the speed - double the size. In this example, 32*(120/97)=40.

38"ZP with Ace 310/Troll 285. Fits nicely in my V1 pouch. I use both vented and non.
YMMV.

Later
Blair

32 av zp with a mojo 260 worked fine for me.