Small diapers hold more?

I'm 5'10" and about 140lbs. slim. and most diapers say they fit a 28-36 inch waist. All the diapers I've worn so far fit but they are all a little big and I feel like a smaller diaper might be able to hold more.

For instance, I'm wearing a small Dry 24/7 right now and it's pretty tight around my legs more so than most diaper. I don't think there is any way these things could leak because of it. And I have a pack of medium Safari's right now that fit and next time I'm going to try a small pack.

Basically what I'm trying to ask is this, If I get a small size diaper would it be able to hold more because it's a tighter fit?

Smaller diapers have less material. Period. So no, a smaller diaper will never be able to hold more. Especially when you're already using confidry. They are among the most absorbent diapers out there. Going smaller than a small confidry will likely put you in a goodnite, or similar. And they don't hold even a quarter a confidry will hold.

The only reason I can think a smaller diaper would hold more assuming same brand / shape / ratings is due to the leak guards potentially having a gap on the larger sizes, the larger the diaper the more absorbent it is due to the increased material as Slomo mentioned.

Depends on what you mean by hold more.

Sheer absorbency amount, no, they simply don't have as much absorbent material.

However a diaper that is too large for you is going to leak sooner than a diaper that is the correct size for you, everything else equal. (ie same diaper different size)

It's not so much small vs big as it is diaper that fits well vs diaper that doesn't. And even then it's not tightness so much as it's how the diaper contours around your body so as to not send liquid on an express trip straight out the leg gathers.

Case in point: I'm skinnier than the OP and I've actually gotten some of the highest capacity out of molicare large. Mostly because it was so large on me that that I was able to fold it around such that liquids couldn't get anywhere near the openings without first traversing an insane amount surface area.

That said, unless you do a lot of experimenting it's a lot easier to get good results right out of the box with a diaper that fits.

some diapers have less padding in their smaller sizes, others just change the size of the shell and wings. Confidry 247 for example are basically identical medium to large, except for the shell dimensions. They're impossible to tell apart when folded up, and can be hard to distinguish even when opened up.

A better fitting diaper won't hold more, but it's probably capable of being fitted better (with correct taping) to get a more leakproof fit than the oversize one.

I have found if the nappy fits better/tighter, then it hold the wetness back longer giving the padding more time to absorb it. Assuming two identical nappies, one fitted tighter around the thighs/leak guards than the other, then there is less chance of leak IMO.