In times past, I thought a 30 or even 40 pound pack for a weekend hike was about right. For the Ptarmigan Traverse, it was closer to 75 lbs. Lately, I've gotten the pack down to 20 pounds pretty easily by lighter gear. A few more years and replacing some older gear, and 15 lbs was pretty doable. My backpack for an overnight trip few weeks ago came in at 12 lbs, the lightest overnight pack I've had. That is the weight without food and water. That weight measurement is called the base weight, and you can figure you will have 2 pounds of food per day, and the volume of water you carry will vary all day.
One thing we know for certain, this is not ultralight:
My usual pack is a 65L or 62L REI Flash pack, whether for a week long trip or an overnight. I got a Golite Jam 50 a year ago, when Golite was still in business. It weighs 2 lbs, and saved a pound over my 65 L pack, and it was about 2/3 full of gear and food. What sold me on it is that it had substantial shoulder pads and waist belt, and a durable fabric. Some ultralight packs don’t have that. It might hold a small bear canister, but not a big one.
When people hear of a weight like that for an overnight, they wonder what creature comforts one has to leave behind, and what discomforts are suffered to geta pack to that weight. Of gear that could be taken, this is the gear which I didn't take that I might have taken on other trips.
camp shoes (Crocs)
Helinox camp chair (REI chair that I did miss)
extra clothes (not having them worked out fine)
big first aid kit (I took band aides and moleskin, and advil)
fishing gear ( I took a Tenkara rod and about 5 flies)
extra camera battery (not needed for a weekend trip)
gloves (it was pretty warm, didn't need them)
commercial bottles of "stuff" (I repackaged stuff like sunblock and bug juice into little bottles)
water filter (I took MSR purification tablets)
I really missed the camp shoes. I ordered some 2 oz shoes what might do the trick. After the trip I also bought some trail runners to replace my over the ankle hiking boots. That won't affect my pack weight, but will save about a ton of weight my feet have to lift. I really missed the camp chair, but I also really liked the light pack weight. A camp chair is a tough one for a 65 y.o. to do without.
Of the big gear I had:
Golite Jam 50 pack, 2 lbs, in which the top 10 inches were empty
Western Mountaineering Mega light bag 27.6 oz (now I’d use the 14 oz Thermarest Vesper) quilt
Tarptent Motrail tent and six stakes:33 oz, an MSR Wing tarp would be lighter
Big Agnes sleeping pad 15 oz
Trail Designs Sidewinder cone and stove, and Snow Peak Ti 900 pot, 8.5 oz
Western Mountaineering down coat 14.5 oz (now I’d use a Mont Bell puffy, which weighs about 6 oz)
nylon long sleeve shirt 8.6 oz
Golite merino wool hat 1.9 oz
REI rain coat 8.7 oz
my 2 oz cork handle knife
Those add up to 9.49 lbs. The other 2.5 pounds were things like wet wipes, toilet paper, sunblock, some repair items, water bottle. I also took my wallet and cell phone, Tenkara rod, which were non-essential.
I also took a small Sony mirrorless camera, not the big Sony R1