Therm-a-Rest
Therm-a-Rest Parsec LT -6 °C Down Sleeping Bag (Regular)
Best use
- Made for
- Backpacking and wild camping
- 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.
- Winter mountain: Comfort rating -1 °C: too cold for winter nights
From the maker's stated use and the published specs.
- Summer wild camp: 6/10 UK, roughly May to September, nights above about 8 °C, sheltered pitches.
- Three-season hills: 6/10 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: 8/10 How much it adds to your pack, compared with the whole market.
Comfort -1 °C, limit -8 °C (EN 13537).
Three-season backpackers who want a light down bag without a cramped cut
- Zip side
- Left
- Comfort
- -1 °C
- Limit
- -8 °C
- Fill
- 900 fill down
- Weight
- 820 g (Regular)
Packed size 6.9 L, 27 cm long and 18 cm across Compare with a 2-litre bottle
About as long as a 2-litre bottle and about one and a half times as wide. Drawn to scale.
Where to buy
Trekitt £386.75 In stock. Free delivery.
View at shop: TrekittUltralight Outdoor Gear £386.99 In stock. Free delivery.
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.
Therm-a-Rest's EN comfort figure of -1 °C sits in the -4.9 to 0 °C band; the limit is -8 °C, colder than the -6 °C in the product name.
Room inside
Estimate from maker's specs: bag shape (fewer than 3 reviews about room) 3/10How much room to move, bend your knees and sleep on your side. Roomier is comfier. 3: Below average. Fine for some trips, not others.
No review we found says how roomy it is, so this is an estimate from the bag shape.
Weight
From maker's figures 8/10How much it adds to your pack. 8: Clearly better than most.
Therm-a-Rest's weight of 820 g sits in the 700–999 g band; Section Hiker's sample was about 40 g heavier and Ultralight Outdoor Gear lists 872 g, both still in that band.
Packed size
From maker's figures 6/10How much room it takes in your rucksack. 6: A bit better than average.
Therm-a-Rest gives a compression sack size of 18 x 27 cm but no volume: about 6.9 L (3.1416 x 9 x 9 x 27 = 6,871 cm³), in 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. "The inside of the Parsec was soft, and I had no negative reactions.".
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. "Even when I was fumbling in the dark for it, it unzipped quite smoothly.".
In short
Good for
- Three-season backpackers who want a light down bag without a cramped cut
- Side and stomach sleepers who sleep warm and still want a mummy bag
- UK spring to autumn hill camps down to about 0 °C
Strengths
- 820 g with 490 g of 900-fill hydrophobic duck down
- Roomier than most mummy bags, which Better Trail and GearJunkie both liked
- 20D recycled nylon shell is tougher than the 10D used on ultralight bags
- Insulated toe pocket and an anti-snag YKK zip that worked well in the dark
Weaknesses
- GearJunkie found small pinholes leaking down after only a week of careful use
- The long, narrow compression sack is hard to repack and the bag packs to about 6.9 L
- Sold in the UK as Parsec LT -6 °C, but the rated limit is -8 °C and comfort -1 °C, so the -6 °C in the name is not the comfort figure
- Not for sustained wet: Better Trail says it suits condensation and light moisture
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.
ShowHide sources (5)
- Therm-a-Rest: Parsec -6 °C Down Sleeping Bag specifications (EU site)
- GearJunkie: Therm-a-Rest Parsec sleeping bag review
- Better Trail: Therm-a-Rest Parsec 20 (2026) sleeping bag review
- Section Hiker: Therm-a-Rest Parsec 20 down sleeping bag review
- Live for the Outdoors: Therm-a-Rest Parsec 20F/-6C sleeping bag review (James Forrest, upgraded-for-2026 model)