Rab
Rab Ascent Down Sleeping Bag (-12°C), 2026 model
Best use
- Made for
- Backpacking and wild camping
- Not for
- Bikepacking
Why these labels
- Backpacking and wild camping: The maker states this use, and the published specs do not rule it out.
- Bikepacking: Bulky for bike bags: packs to 15.2 litres
From the maker's stated use and the published specs.
- Summer wild camp: 5/10 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: 8/10 UK winter or high ground. Below freezing, strong wind, possibly snow.
- Weight: 4/10 How much it adds to your pack, compared with the whole market.
Comfort -5 °C, limit -12 °C (ISO 23537).
Lowest price we found
£304.99 at Ultralight Outdoor Gear
Go to Ultralight Outdoor Gear Compare 2 shopsSide sleepers and restless sleepers who want a wide mummy cut and a roomy foot box
- Zip
- Half
- Comfort
- -5 °C
- Limit
- -12 °C
- Fill
- 650 fill down
- Weight
- 1.35 kg (Regular)
Packed size 15.2 L, 40 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 £304.99 In stock. Free delivery.
View at shop: Ultralight Outdoor GearRab £360 In stock. Free delivery.
View at shop: RabAlpinetrek £359.95 Out of stock. Regular out of stock; Regular wide and X-long wide in stock.
View at shop: AlpinetrekPrices 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 9/10How cold a night you can sleep comfortably through. 9: Among the best you can buy for this.
Rab's ISO 23537 comfort -5 °C (limit -12 °C, extreme -33 °C) sits in the -5 °C or colder band. The maker's figure, not re-tested.
Room inside
Estimate from maker's specs: maker's shoulder girth (fewer than 3 reviews about room) 8/10How much room to move, bend your knees and sleep on your side. Roomier is comfier. 8: Clearly better than most.
No review we found says how roomy it is, so this is an estimate from the maker's shoulder girth.
Weight
From maker's figures 4/10How much it adds to your pack. 4: A bit below average.
Rab lists 1,350 g for the Regular, in the 1,300-1,699 g band. Ultralight Outdoor Gear lists 1,376 g, the same band.
Packed size
From maker's figures 1/10How much room it takes in your rucksack. 1: A real weak point.
Rab gives only two figures, 22 cm x 40 cm, so it is a stuff sack: 3.1416 x 11 x 11 x 40 = 15,205 cm3, 15.2 L, in the 13 L+ band.
In short
Good for
- Side sleepers and restless sleepers who want a wide mummy cut and a roomy foot box
Strengths
- 680 g of 650 fill power duck down with a fluorocarbon-free hydrophobic finish
- Wide mummy shape with sidewall baffles, a roomy foot box and an extra arm vent zip
- Comes in Regular, Regular wide, Long and Long wide, plus a Women's version
Weaknesses
- 1,350 g and about 15.2 L packed: heavier and bulkier than the Neutrino -12 (1,070 g, 11.0 L) at the same rating
- 650 fill power down needs more weight for the same warmth than the 800 fill power in the Neutrino
- Down loses warmth if it stays soaked, so a long wet trip favours a synthetic bag
- No independent review of the 2026 Ascent found yet, so Damp, Comfort and Durability are estimates, not reviewed scores
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.