Recommendations for one pack for both day and 3-5 nighters

Zimmerbuilt Quickstep?  Light enough to be a day pack (lighter than most), but over 36 liters with the outside pockets.  Pair that with a waist pack and I might fit a small overnight load in good weather.

I think many of the UL 40L packs might work better depending on the volume of your kit.

“My MLD Hell is my daypack and comfortably fits an overnight load.”

Who the…heck came up with that name? “When you think of hiking, go to Hell, or…go elsewhere”. I’d  go elsewhere.  Kudos for persevering!

Hell pack fits an overnight load

What are your other big 3 items .. and insulation if you don’t mind me asking?

Following this thread as I’m looking at something similar. I’ve had to switch to a running vest style pack, the Cutaway in 20”, due to sore hips (i.e. no major hipbelt … hopefully temporary), and now debating on a small volume pack altogether.

I have two packs currently.

Wait I forgot about my beloved GG Kumo. I have carried that in the Sierras with 3.5 days of food in a Bearboxer Contender with a bug bivy and SMD Deschutes tarp. It was definitely overstuffed and I don’t think I would want to push that to 5 days but that’s a great pack and would work as a larger daypack. It’s in between my Hell and Atom+ in size.

Just got a custom Zimmerbuilt Quickstep in Xpac with ultragrid in lieu of mesh on the back and am thoroughly impressed. Fit and finish is fantastic. Chris made the pack in only a day or two and I had it in my hands 4 days from the time I ordered. 12oz. It’s my day pack and summer quick trip pack. If your UL gear is dialed in I could see 3-5 days with this.

I can see why the panel loading could be an issue if thats not your preference, but I don’t see how a 35L backpack can be too big for hiking.

I would hesitate to go smaller than 30-35L for anything except a running backpack, where bouncing items is a real concern. For anything else I’d rather have excess space than a stuffed pack.
Having excess space in a hiking daypack also makes it so much more flexible; room for extra layers for all season/all weather hikes, room for extra gear if combining your hike with other activities like photography, fishing, skiing etc.

Personally I’d be much more worried about having too little space in a 3-5 nighter backpack.
Living in a rather cold climate, my Bergans Helium 55L is the smallest I’d go for a 3-5 day hike, and while it would work for day hikes, it’s not ideal.
Day hikes is probably 85% my hiking, so having a separate backpack for this (several actually) makes sense. It saves my multi day backpacks from unnecessary wear, which is nice since I choose thinner and lighter materials for these packs. And I can optimise my packs with features that are suited for the different activities. So while the minimalistic simplicity of one pack for everything is an appealing thought, it would be too much of a compromise for me.

I need a bear canister where I hike, so this pack is out

Read where the YamaMtngear Sassafras can carry a BV500 and the Nashville Cutaway a BV450 … both internally.  IMHO one may need a very compressible EE down quilt in 950 fill/7d fabric all over .. and other ultralight yet ultra-compressible gear too.  Hope I read those right and not reading too much into said packs loosing the hipbelt myself..

One hiker/fast packer is claiming a BV 425 inside of a Pa’lante Joey (iirc) though with a definite summertime packing list of S2S poncho-tarp, summer quilt, etc.. with all the running madness (if it’s too cold, speed up! .. not that I’ll partake with alpha-direct head-to-toe now).

do do fast packers stay out for five nights? I honestly don’t know. That’s not me.

Not me either but they’ve been on the long trails (FKTs, “YoYo’s”, etc..).  I’m more interested in their kit to apply to long summer days (and of course to fit it all in a smaller volume ultralight pack as per the OP). .

The question with diminutive packs is whether the users can stay “bear can” legal?  So some trip reports on Reddit have some of these packs being able to carry a bear vault, but how much other gear?  In summer, it may not need to carry much more than said bear can.

There’s also doing big enough miles to [hopefully] make it at an overall faster pace to the next town and restaurant.   If not they’ll be really ultralight I suppose (that’s where the bar of pemmican should fit in).  Especially the latter may not be what the OP is looking for, just to add.

I like my granite gear crown-2 60.  It’s a roll-top and can be used with or without the crown.  Never used it as a daypack, though it could be done.  It does hold a bear canister.

Wow, so far packs ranging from the Zimmerbuilt to the ULA Catalyst have come up. Doug–the OP–where are you? what do you think; what are your ideas in light of this discussion; what have you decided? We want to know!

Personally, I think Doug is asking the impossible. He wants a day pack that will work for five days out backpacking. He wants a mule that will run like a horse. Ain’t gonna happen. Get two distinct packs.