A sleeping bag only has to do two things well: keep you warm, and not weigh down your pack while it does it. The Alpkit Pipedream 400 is a 3-season down bag built around that trade-off. It's rated to a -6°C limit but weighs well under a kilogram. I took the long version out from early spring into summer last year to see how it holds up.
Warmth: the number that actually matters
Alpkit rates the Pipedream 400 to a -6°C (21°F) limit. That's the number on the label, but it's not the number that matters for actually sleeping well. That's the comfort rating, -4.2°C (24°F). Plan around the comfort figure, not the limit, and this bag sits squarely in 3-season territory: spring through to early autumn in the UK, or summer trips at altitude.
The fill is 750 fill power DownTek hydrophobic down, certified to the Responsible Down Standard (RDS), packed into a box-wall construction that keeps it evenly spread rather than shifting into cold spots, with a 20-denier polyester inner and outer. The outer also has a DWR (durable water repellent) coating, which buys you some margin against damp air or a wet tent wall. It sheds light moisture, but it's not a substitute for keeping the bag dry, and down still loses its loft if it gets properly wet, treated or not.
Size and weight
At 5ft 11in, I went for the long version. Here's how the two sizes compare:
Regular
Long
Internal length
190cm
210cm
Internal width
75cm
75cm
Bag weight
865g
910g
Pack size
⌀25 × 18cm
⌀28 × 21cm
The included stuff sack is generously sized, so there's no fight to get the bag back in, and it has two cinch cords that compress it right down. Packed, the long version comes out slightly bigger than the size of a large water bottle.
It also comes with a separate, larger storage sack for between trips. Worth using it: down left compressed in the stuff sack for weeks at a time loses its loft, and with it some of its warmth, so the storage sack is there to keep it stored loose.
Sleeping in it
It's a very comfortable bag. There's enough room in the long version to shift position without feeling boxed in, and the neck baffle (not something everyone gets on with) never felt like it was in the way when I didn't need it, or an afterthought when I did.
The zip is a single YKK, running about three-quarters of the way down rather than the full length, and it doesn't snag on the liner the way a cheaper zip can. You can also choose which side it's on, left or right, when you order.
The neck baffle on the Alpkit Pipedream 400
The wider Pipedream range
The 400 sits in the middle of Alpkit's Pipedream line, and the Regular/Long split covers pretty much everyone. At 5ft 11in, the long fit me with room to spare. Where it's worth pausing is the temperature range: if -4.2°C comfort is warmer than you need, the Pipedream 200 is the lighter, summer-only option; if you're regularly out in colder shoulder-season or winter conditions, the 600 goes warmer. Worth checking those against your own trips before you commit to the 400.
Verdict
The Pipedream 400 doesn't try to be more than it is: a lightweight, warm 3-season mummy bag that packs down small and gets on with the job. It comes with Alpkit's 3-year Alpine Bond, so if something does go wrong, you're covered. If you're after a dependable spring-to-autumn bag that won't weigh down your pack on a multi-day trip, this is a straightforward one to recommend.
