Therm-a-Rest
Therm-a-Rest Questar -6 °C Down Sleeping Bag (Regular)
Best use
- Made for
- Backpacking and wild camping
- Also works for
- Bikepacking
- Not for
- Winter mountain
Why these labels
- Backpacking and wild camping: The maker states this use, and the published specs do not rule it out.
- Bikepacking: Small enough for bike bags: packs to 5 litres
- Winter mountain: Comfort rating 0 °C: too cold for winter nights
From the maker's stated use and the published specs.
- Summer wild camp: 7/10 UK, roughly May to September, nights above about 8 °C, sheltered pitches.
- Three-season hills: 7/10 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 0 °C, limit -6 °C (EN 13537).
No shop we checked has it in stock
Three-season wild camps in the UK, spring to late autumn, with a decent mat
- Zip
- Half, left side
- Comfort
- 0 °C
- Limit
- -6 °C
- Fill
- 650 fill down
- Weight
- 1.0 kg (Regular)
Packed size 5 L, 22 cm long and 17 cm across Compare with a 2-litre bottle
Shorter than a 2-litre bottle and about one and a half times as wide. Drawn to scale.
Where to buy
Absolute Snow £309.95 Out of stock. Shop page says currently unavailable. Full price. Free delivery over £100.
View at shop: Absolute SnowUltralight Outdoor Gear £244.99 Out of stock. Regular out of stock on 2 Nov 2026 (the Long is in stock at £274.99). Page shows RRP £309.99; free UK delivery over £15.
View at shop: Ultralight Outdoor GearPrices checked 2 Nov 2026 to 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.
The maker's EN 13537 comfort figure is 0 °C (limit -6 °C, extreme -23 °C), which sits in the -4.9 to 0 °C band. The maker's figure, not re-tested.
Room inside
Estimate: only 2 reviews about room inside (fewer than the 3 we need, so never above 8) 8/10How much room to move, bend your knees and sleep on your side. Roomier is comfier. 8: Clearly better than most.
Two reviewers say it is roomy enough to roll onto your side and turn over inside the bag.
Weight
From maker's figures 6/10How much it adds to your pack. 6: A bit better than average.
1,002 g for the Regular sits in the 1,000-1,299 g band, only 2 g inside it. Older listings and Live For The Outdoors give 990 g, which would be the 700-999 g band, so treat it as borderline.
Packed size
From maker's figures 7/10How much room it takes in your rucksack. 7: Better than most.
The maker's table gives 22 x 17 cm packed. Working that roll as a cylinder gives 3.1416 x 8.5 x 8.5 x 22 = 4,994 cm3, about 5.0 L, in the 4-5.9 L band. REI lists 5.4 L, the same band. Older sources quote 23 x 19 cm, about 6.5 L, which would be the 6-8.9 L band.
What reviewers say (out of 10)
Ratings marked * are from reviews and are not part of the trip score. They are reviewers' scores, not our own measurements. How we score
Comfort to sleep in*
Reviewers' average 8/10How comfy the shape, hood and fabric feel; not the temperature rating.
4 reviews on comfort, e.g. "They both have that “shiny” feel to them, but are very comfy and soft too.".
Reviewers disagree on this.
Zip*
Estimate: only 2 reviews about the zip (fewer than the 3 we need, so never above 8) 8/10How smoothly the zip runs without snagging.
2 reviews on the zip, e.g. "the solid, anti-snag zip".
In short
Good for
- Three-season wild camps in the UK, spring to late autumn, with a decent mat
- Restless and side sleepers who find a tight mummy bag restrictive
Strengths
- Roomy cut with box baffles and zoned insulation (more down on top and sides than underneath)
- Removable straps hold the bag to your mat, so you do not roll off it
- 650-fill down with a hydrophobic treatment, 540 g of fill, Responsible Down Standard certified
- Packs to about 5 L and weighs 1,002 g in the Regular, with a compression sack and a storage sack included
- Draught collar, full-length zip draught tube, snag-free zip and an external zip pocket
Weaknesses
- Comfort rating is 0 °C, so cold sleepers should plan on layers or a warmer bag for sub-zero nights
- The foot-warmer pocket got in the way of one reviewer who sleeps on their side
- Short on independent evidence: no usable review scores how it copes when damp, only two cover comfort and only one touches durability, so those three are estimates, not reviewed scores
- Spec sources disagree on weight and packed size (990 g and 23 x 19 cm in older listings, 1,002 g and 22 x 17 cm in the maker's current table)
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.
ShowHide sources (5)
- Ultralight Outdoor Gear: Therm-a-Rest Questar 20 down sleeping bag (spec table: ratings, weight, fill, packed size)
- Live For The Outdoors: Therm-a-Rest Questar 20F/-6C tested and reviewed (James Forrest)
- Great Walks: Review of the Therm-a-Rest Questar 20 sleeping bag (Dan Slater)
- Outside Bozeman: Review of the Therm-a-Rest Questar sleeping bag
- UKHillwalking: Therm-a-Rest Questar -6C Sleeping Bag and Trail Pro Mat review (John McKenna, Rockfax)