I'm trying to decide on daysack for light hiking (no mountains, clement weather). There's plenty of guides online, but I can't seem to make sense of them.
This one, for example says
Most daypacks fall under this category. These are made to include the essentials such as food for the day, light insulation layers (puffy or fleece jacket), rain shell, a headlamp, a small first aid kit, and a space blanket.
This is the category where most weekend and overnight backpacks fall under.
These backpacks could fit everything you’d need for a 2 or 3-day adventure, including a lightweight sleeping bag, food for up to 6 meals, hammock/lightweight tarp/ultralight one-person tent, small sleeping pad, underwear, and an extra pair of socks.
There are loads of similar examples on hiking websites and YouTube.
I've measured my stuff (plus some official measurements from the websites of stuff I haven't bought yet (I'm new to this)
Tent - 6l
Sleeping bag -8l (compressed)
Bedmat - 2l
2l extra water
1l extra food
4l spare clothing
1l cooking pot
(I also measured all my day hike stuff using the DoE kit list - It comes to 15l)
That's 24l bare minimum for my overnight additions. So I can't see how whatever pack I get for camping, my daysack isn't going to want to be at least 24l less.
Yet every website and video I seem to find has a difference of less than half that (10l in the example above). Even the ultra lightweight stuff doesn't seem to gain much in volume (just weight).
So my question is basically what are people carrying in a daysack that needs 20-30l, and how are they adding only 10l to that to turn it into an overnight camping bag?