Sierra Designs
Sierra Designs Backcountry Bed Down Sleeping Bag (-9 °C)
Where it fits
- Also works for
- Backpacking and wild camping
- Not for
- Bikepacking, Winter mountain
Why these labels
- Backpacking and wild camping: Light to carry: 1.1 kg
- Bikepacking: Bulky for bike bags: packs to 15.6 litres
- Winter mountain: Comfort rating -2.2 °C: too cold for winter nights
From the maker's stated use and the published specs.
- Summer wild camp: 4/10 UK, roughly May to September, nights above about 8 °C, sheltered pitches.
- Three-season hills: 5/10 UK hills in spring and autumn. Wind, rain, and nights near freezing.
- Winter camp: 4/10 UK winter or high ground. Below freezing, strong wind, possibly snow. Capped at 4: needs warmth 9+ (comfort -5 °C or colder).
- Weight: 6/10 How much it adds to your pack, compared with the whole market.
Comfort -2.2 °C, limit -8.9 °C (ISO 23537).
Side and stomach sleepers who hate being wrapped in a mummy bag
- Zip
- None, none
- Comfort
- -2.2 °C
- Limit
- -8.9 °C
- Fill
- 650 fill down
- Weight
- 1.09 kg (Regular)
Packed size 15.6 L, 41 cm long and 22 cm across Compare with a 2-litre bottle
A bit longer than a 2-litre bottle and about twice as wide. Drawn to scale.
Where to buy
Ultralight Outdoor Gear £289.99 In stock. Free delivery. Regular. Shop RRP £309.99. Only UK shop found; Sierra Designs' own page shows it sold out.
View at shop: Ultralight Outdoor GearPrices checked 8 Nov 2026 on each shop's own page; shops can change them. We earn no commission on these links; shops are listed by price. More
Our ratings (out of 10)
1 to 10, compared with the whole market. Each says what it's based on. How we score
Warmth
From maker's figures 7/10How cold a night you can sleep comfortably through. 7: Better than most.
Sierra Designs' ISO comfort -2.2 °C (limit -8.9 °C) sits in the -4.9 to 0 °C band; one reviewer found the comfort figure ambitious and felt comfortable only down to about 2 °C.
Room inside
Estimate from maker's specs: bag shape (fewer than 3 reviews about room) 5/10How much room to move, bend your knees and sleep on your side. Roomier is comfier. 5: Does the job. Average for wild-camping gear.
No review we found says how roomy it is, so this is an estimate from the bag shape.
Weight
From maker's figures 6/10How much it adds to your pack. 6: A bit better than average.
1,090 g (Regular, Sierra Designs' figure; one shop lists 1,176 g) sits in the 1,000–1,299 g band.
Packed size
From maker's figures 1/10How much room it takes in your rucksack. 1: A real weak point.
Sierra Designs gives a stuff sack of 41 x 22 cm (length x width), so 3.1416 x 11 x 11 x 41 = 15,585 cm³, so 15.6 L, in the 13 L+ band; one reviewer could only just fit it into a small compression sack.
In short
Good for
- Side and stomach sleepers who hate being wrapped in a mummy bag
- Car camping, base camps and short backpacking trips where weight and pack size matter less
Strengths
- Zipperless quilt-style opening, so there is no zip to twist round or snag
- Self-sealing foot vent and a roomy cut let you sit up, move and vent heat
- Sleeping-mat sleeve keeps the mat under you, so the bag has no insulation under the torso
- Comfort rating of -2.2 °C (limit -8.9 °C)
- OutdoorGearLab scored its comfort 10 out of 10
Weaknesses
- Bulky: about 15.6 L in its stuff sack
- Heavy for a down bag at 1,090 g, and Sierra Designs' figure and one shop's (1,176 g) differ
- The quilt front needs tucking in on cold nights or it can be draughty
- Down is 650-fill, a lower grade than most backpacking bags, and there are only two independent reviews of this version, so comfort, damp and durability are 'Not enough evidence'
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.