When we were kids it was big enough to slide down it! Landed in a soft pile of dirty clothes. I vote big.

My sister and I did the same thing I would go as big as you can

small and not vertical could have issues, i think it would be tiresome to not be able to stuff sheets in willy nilly, have a nice pusher tool available.

@jodyfhyland, thanks for the advice! Is yours more like mine where it is a slide compared to the typical vertical chutes? How big is your chute's diameter?

Not joking now :) in our last house the chute was smaller, not sure diameter, and was slanted. Things often became stuck, so we just stopped using it altogether. The house was built in 1962 and I think towels, etc were not as plush. If I were building it fresh I would for sure make big enough to fit today's plusher items.

Ours is actually vertical (which I didn't even realize until looking at it again!). The diameter is only a foot but we've never had a problem with things getting stuck. I really think you could do 14-15" without a problem. Clothing won't be an issue. With bedding, you may have to separate entire sets (fitted sheet, flat sheet, pillow cases) rather than putting it all down at once but if smaller is your preference, I don't think you'll have any problems. Going bigger would make putting larger amounts down easier but how often will you be putting that much down at once? Just having a laundry chute is wonderful so separating things here and there doesn't bother me. Hope that helps!