Footbox at a glance
- Coldest spot
- In most sleep systems
- Quilt options
- Sewn closed or open
- Wants
- Extra volume, not compression
Why feet get cold first
Feet are the hardest part of the body to keep warm at night. They're furthest from your core, they produce little heat of their own, and they press insulation flat against the pad from the inside. The footbox is the design response to all three.
What a good footbox does
A good one is cut with extra volume so your toes don't compress the down, and it's often built with a trapezoidal or rounded shape that lets feet rest naturally rather than being held pointed. Some bags add extra fill down there specifically, which is one of the cheapest ways to make a bag feel warmer than its rating.
Closed or open, on a quilt
Quilts split into two camps here, and it's the main decision when buying one. A sewn, closed footbox is warmer and simpler and stops draughts completely. A zipped or snapped footbox opens flat so the quilt doubles as a blanket in summer, at the cost of a seam that can leak warmth and some fiddling in the dark. Neither is wrong; pick based on whether you want one quilt across seasons.
What this means when you're choosing
- Extra fill or a differential cut at the foot end
- On a quilt, whether the footbox is closed or opens flat
- Enough width to sleep with feet apart rather than pointed
The common mistake
Buying an open footbox and never closing it
An open footbox is a genuine choice for warm nights and a genuine problem on cold ones if you do not cinch and clip it properly. Practice closing it at home; doing it for the first time in the dark at 28F does not go well.
Common questions
Why are my feet always cold in a sleeping bag?
Partly circulation, partly that your toes compress the insulation against the pad. A roomier footbox helps, and so do dry socks put on specifically for sleeping and a pad with enough R-value under your feet.
Should I get a quilt with a closed or open footbox?
Closed if you mostly hike in the shoulder seasons and want the warmth. Open if you want one quilt that also works as a summer blanket and you don't mind a slightly draughtier foot end.