I've just acquired a new loveseat for my apartment that's in desperate need of reupholstering. Here's the problem: the cushions are (or were) stuffed with wool. I have some experience with reupholstering furniture in the past, but I've never worked on something like this before and I can't seem to find any information that might give me an estimation on how much I'd need to re-stuff these cushions.

Is there a rule of thumb for this?