Therm-a-Rest
Therm-a-Rest Questar 0 °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 5 °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: 4/10 UK hills in spring and autumn. Wind, rain, and nights near freezing. Capped at 4: needs warmth 7+ (comfort 0 °C or colder).
- 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: 7/10 How much it adds to your pack, compared with the whole market.
Comfort 5 °C, limit 0 °C (EN 13537).
Side sleepers and restless sleepers who find mummy bags too tight
- Comfort
- 5 °C
- Limit
- 0 °C
- Fill
- 650 fill down
- Weight
- 850 g (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
Ultralight Outdoor Gear £219.99 In stock. Free delivery.
View at shop: Ultralight Outdoor GearWildbounds £178.95 Out of stock.
View at shop: WildboundsPrices 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 5/10How cold a night you can sleep comfortably through. 5: Does the job. Average for wild-camping gear.
Therm-a-Rest's EN comfort figure of 5 °C sits in the 0.1 to 5 °C band; the limit is 0 °C, so it is a summer and shoulder-season bag.
Room inside
Estimate: only 1 review 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.
One reviewer says it has lots of room in the top half and suits a side sleeper who tosses and turns.
Weight
From maker's figures 7/10How much it adds to your pack. 7: Better than most.
Therm-a-Rest's weight of 850 g sits in the 700–999 g band; UKHillwalking weighed a Regular at 854 g without its sack.
Packed size
From maker's figures 7/10How much room it takes in your rucksack. 7: Better than most.
Therm-a-Rest gives a packed size of 17 x 22 cm: about 5.0 L (3.1416 x 8.5 x 8.5 x 22 = 4,994 cm³), in the 4–5.9 L band. UKHillwalking quotes 4 L, also in that 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.
3 reviews on comfort to sleep in, e.g. "I appreciated the roomier hood design that also accommodates a Therm-a-Rest Airhead or other camp pillow.".
Zip*
Reviewers' average 10/10How smoothly the zip runs without snagging.
3 reviews on zip, e.g. "The snag-free zipper really is nicely designed, I feel it's hard to actually try to snag this".
In short
Good for
- Side sleepers and restless sleepers who find mummy bags too tight
- Summer and shoulder-season UK camps, including car camping and bivvying
Strengths
- Roomy W.A.R.M. cut lets you lie on your side and move around, praised by all three reviewers
- 650-fill hydrophobic down, so a damp tent or dewy morning is less of a worry
- Full-length zip with draft tube and an insulated pocket for cold feet
- About 850 g and 5 L packed, small enough for backpacking
Weaknesses
- EN comfort is only 5 °C: not for cold UK nights, and UKHillwalking added layers near 0 °C
- Not light for its warmth: UKHillwalking notes lighter bags with the same rating exist
- The wide cut can spill over a narrow mat when bivvying, and the hood takes some adjusting
- The reviews date from 2019 to 2021
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.
ShowHide sources (5)
- Therm-a-Rest: Questar 0 °C Sleeping Bag specifications (EU site)
- GearJunkie: Therm-a-Rest Questar 32 sleeping bag review
- UKHillwalking: Therm-a-Rest Questar sleeping bag and ProLite Apex mat review
- The Outbound: Review of the Thermarest Questar 0 °C
- Jeger.no: Test av Therm-a-rest Questar 0C (Norwegian)