Rab
Rab Storm Bivi bivvy bag (230 cm long)
- Weight: 7/10 How much it adds to your pack.
- Rain protection: 7/10 How well the fabric keeps out heavy, long rain.
- Packed size: 8/10 How much room it takes in your rucksack.
Cold-weather and mountain nights where a roomy bag is needed for a bulky winter sleeping bag
- Style
- Flat
- Weight
- 547 g
- Fabric
- 10,000 mm
- Floor
- 10,000 mm
- Inner length
- 230 cm
Packed size 2.8 L, 25 cm long and 12 cm across Compare with a 2-litre bottle
About as long as a 2-litre bottle and a bit wider than one. Drawn to scale.
Where to buy
Ultralight Outdoor Gear £124.99 In stock. Free delivery.
View at shop: Ultralight Outdoor GearAbsolute Snow £83.95 Out of stock. Shop page says currently unavailable. Free delivery over £100; under that the charge depends on weight and shows only in the basket.
View at shop: Absolute SnowRab £145 Out of stock. Out of stock when checked (Ascent Red and Chlorite Green).
View at shop: RabPrices 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
Weight
From maker's figures 7/10How much it adds to your pack. 7: Better than most.
Rab gives 547 g (Rab's own Weight line; its text says 'At 547g'), in the 400–599 g band. Ultralight Outdoor Gear lists 572 g, which is in the same band.
Rain protection
From maker's figures 7/10How well the fabric keeps out heavy, long rain. 7: Better than most.
Rab gives 10,000 mm hydrostatic head for the 40D polyurethane-coated nylon top and 10,000 mm for the 70D base, in the 10,000–14,999 mm band. The floor is over the 2,000 mm line, so nothing is taken off.
Packed size
From maker's figures 8/10How much room it takes in your rucksack. 8: Clearly better than most.
Rab gives 25 cm x 12 cm: 3.1416 x 6 x 6 x 25 = 2,827 cm³, about 2.8 L, in the 2.5–3.9 L band.
In short
Good for
- Cold-weather and mountain nights where a roomy bag is needed for a bulky winter sleeping bag
- Rocky or rough pitches, where the 70D base takes the wear
- Bikepacking and multi-day treks as a cheap tent-free shelter (547 g, packs to about 2.8 L)
Strengths
- Tough 70D (160 g/m²) base, much heavier than the 40D top
- Large cut with 3D construction: 230 cm long and 80 cm across the shoulders, for bulky clothing or a big sleeping bag
- Zipped main entry with a mesh panel for venting
- 10,000 mm hydrostatic head on both the top and the base
Weaknesses
- Breathability is 10,000 g/m²/24 h, half the 20,000 of Rab's Pertex Shield Air bags, so condensation is a risk when sealed
- Heavier than Rab's other flat bags at 547 g, against 440 g for the Alpine Bivi and 406 g for the Trailhead
- No independent test of the current model was found, so condensation, comfort and durability are estimates, not reviewed scores
- Flat bag with no pole: the fabric rests on your face and bag when zipped up
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.