3 photosLightest#1
Rab
Rab Ark Emergency Bivi
The lightest bag on test from a British mountaineering brand.
- Weight
- 105 g
- Thermal
- Reflective
- Packed
- 12 × 6 cm
- Waterproof
- Windproof
- Heat reflective
- Taped seams
From
£18
at Rab
UK Emergency Sleeping Bag & Bivy Sack Comparison
The bag that lives at the bottom of your pack all year. Nine UK-available options from a £5 polythene sack to a mountain-rescue grade insulated bag.
9 products, lightest first
- 3 photosLightest#1Full specs, 2 retailers →View Deal
5 photosBest all-rounder#2Survive Outdoors Longer
SOL Emergency Bivvy
The benchmark reflective bivvy: sealed seams, 90% heat return, and a rescue whistle.
- Weight
- 108 g
- Thermal
- High reflective
- Packed
- 13 × 8 × 2 cm
- Waterproof
- Windproof
- Heat reflective
- Whistle included
- Reusable
Full specs, 3 retailers →View DealFrom
£19.99
at Needle Sports
2 photosBest value reflective#3Lifesystems
Lifesystems Heatshield Thermal Bag
DofE-recommended metallised bag that packs smaller than a drinks can.
- Weight
- 110 g
- Thermal
- High reflective
- Packed
- 7 × 6 × 6 cm
- Waterproof
- Windproof
- Heat reflective
- Taped seams
Full specs, 3 retailers →View DealFrom
£10.95
at Cotswold Outdoor
2 photosTwo-person#4Ortovox
Ortovox Bivy Ultralight
A 150 g emergency bivy for one or two people that packs to 5 × 5 × 9 cm.
- Weight
- 150 g
- Thermal
- Reflective
- Packed
- 5 × 5 × 9 cm
- Waterproof
- Windproof
- Heat reflective
- 1–2 person
- Stuff sack
Full specs, 3 retailers →View DealFrom
£21.28
at Alpinetrek
2 photosBest breathable#5Survive Outdoors Longer
SOL Escape Lite Bivvy
A breathable bivvy you can actually sleep in without waking up soaked.
- Weight
- 156 g
- Thermal
- Reflective
- Packed
- Not stated by maker
- Breathable
- Heat reflective
- Windproof
- Reusable
Full specs, 2 retailers →View DealFrom
£48.35
at Oliunid
5 photosCheapest#6Highlander Outdoor
Highlander Emergency Survival Bag
The cheapest way to tick the survival-bag box on a kit list.
- Weight
- 260 g
- Thermal
- Barrier only
- Packed
- Not stated by maker
- Waterproof
- Windproof
- Reusable
Full specs, 2 retailers →View DealFrom
£4.99
at Highlander Outdoor
Reusable ripstop#7Ortovox
Ortovox Bivy Single
A tough, reusable 70D ripstop emergency bivy for one: 280 g with a rolltop stowaway bag.
- Weight
- 280 g
- Thermal
- Barrier only
- Packed
- 6.5 × 22 cm
- Windproof
- Water repellent
- Ripstop fabric
- Reusable
- Rolltop stuff bag
Full specs, 2 retailers →View DealFrom
£48.71
at Alpinetrek
10 photosBest for two#8Lifesystems
Lifesystems Survival Bag
The heavy-duty orange polythene bag every UK mountain leader carries.
- Weight
- 290 g
- Thermal
- Barrier only
- Packed
- 10 × 18 × 3 cm
- Waterproof
- Windproof
- Fits 2 people
- Reusable
Full specs, 3 retailers →View DealFrom
£5.99
at Cotswold Outdoor
6 photosWarmest#9Blizzard Protection Systems
Blizzard 3-Layer Survival Bag
Mountain-rescue kit: three insulating Reflexcell layers vacuum-packed flat.
- Weight
- 385 g
- Thermal
- Insulated
- Packed
- 23 × 11 × 4 cm
- Waterproof
- Windproof
- Heat reflective
- Reusable
Full specs, 3 retailers →View DealFrom
£40.79
at Medisave
Weights and sizes are manufacturer figures. Prices were checked on 31 October 2026 and change daily, so confirm on the retailer's site.
How to choose emergency bivvies
Weight you will actually carry
A bag that lives in your pack all year should be under 150 g. The reflective bags from SOL, Lifesystems and Rab all qualify. Plain polythene bags are two to three times heavier.
Reflective, insulated, or just a barrier?
Polythene bags only stop wind and rain. Metallised bags reflect most of your radiated heat back. Only a cellular bag such as the Blizzard traps still air, which is what real insulation needs.
Sealed seams and packed size
Look for heat-sealed or taped seams; glued ones leak. The Lifesystems Heatshield packs to the size of a tennis ball, while the Blizzard needs a flat slot in a lid pocket.
Single use or reusable?
Thin foil bags are effectively single use once unpacked. If you want to practise with it, or sleep in it on purpose, pay more for a breathable bag like the SOL Escape Lite.
Methodology
Where these numbers come from
Specs are manufacturer figures, or a UK specialist retailer's spec sheet where the maker is vague. Prices were checked on 31 October 2026. Our ratings are editorial and explained on the how we test page.
Sources
- 1SOL Emergency Bivvy spec sheet (Needle Sports)
- 2SOL Emergency Bivvy, manufacturer page
- 3SOL Escape Lite Bivvy (Needle Sports)
- 4Lifesystems Heatshield Thermal Bag (Cotswold Outdoor)
- 5Lifesystems Survival Bag, manufacturer page
- 6Rab Ark Emergency Bivi, manufacturer page
- 7Blizzard 3-Layer Survival Bag, manufacturer page
- 8Blizzard Survival Bag features and tog rating (Steroplast)
- 9Highlander Emergency Survival Bag, manufacturer page
- 10Ortovox Bivy Ultralight product page
- 11Wilderness Times review
- 12Alpinetrek listing
- 13Hardloop listing
- 14Absolute Snow listing (dimensions)
- 15Ortovox Bivy Single product page
- 16Alpinetrek listing
- 17Hardloop listing