The JanSport Katahdin 40 is one of the two smallest backpacks we tested in our ultralight backpack review, and it also has one of the worst weight-to-volume ratios. What this pack does have going for it is far and away the most affordable price tag. At $80 full retail, it is a great option for folks looking for an everyday dayhiking pack with just enough volume for multi-day backpacking trips with very light loads.
Folks seeking the best deal on a very functional ultralight pack that can handle loads for week-long trips should consider our Best Buy winner, the Osprey Exos 48. The Exos is one of the highest scoring packs overall, plus it's relatively affordable compared to the other top-scoring packs. That said, it's still fairly pricey.