Prices checked 28 October 2026 · 7 bags compared
Comparing pack weight, thermal reflectivity, waterproof ratings, and prices across UK outdoor retailers.
Featured comparison
Seven bags you can buy in the UK today, from a £5 polythene sack to a mountain-rescue grade insulated bag. Specs are from the makers; prices were checked on 28 October 2026.
7 products, lightest first
Lightest#1Rab
The lightest bag on test from a British mountaineering brand.
Reflects body heat; windproof and waterproof
Material: Lightweight polyethylene, taped seams. Opens to Single person.
Best all-rounder#2Survive Outdoors Longer
The benchmark reflective bivvy: sealed seams, 90% heat return, and a rescue whistle.
Reflects 90% of body heat
Material: Heat-reflective polyethylene, heat-sealed seams. Opens to 213 × 91 cm.
Best value reflective#3Lifesystems
DofE-recommended metallised bag that packs smaller than a drinks can.
Retains over 90% of radiated body heat
Material: Metallised low-density polyethylene, taped seams. Opens to 210 × 90 cm.
Best breathable#4Survive Outdoors Longer
A breathable bivvy you can actually sleep in without waking up soaked.
Reflects 70% of body heat while letting vapour escape
Material: Breathable spun-bonded olefin with metallised coating. Opens to 213 × 81 cm.
Cheapest#5Highlander Outdoor
The cheapest way to tick the survival-bag box on a kit list.
Windproof and waterproof barrier; no reflective layer
Material: Polyethylene. Opens to 180 × 90 cm.
Best for two#6Lifesystems
The heavy-duty orange polythene bag every UK mountain leader carries.
Windproof and waterproof barrier; no reflective layer
Material: Heavy-duty polyethylene, welded seams. Opens to 210 × 105 cm.
Warmest#7Blizzard Protection Systems
Mountain-rescue kit: three insulating Reflexcell layers vacuum-packed flat.
Rated around 7 tog: insulates, not just reflects
Material: Triple-layer Reflexcell metallised cellular film. Opens to 230 × 80 cm.
Weights and sizes are manufacturer figures. The thermal rating is a SleepGear editorial score from 1 (minimal) to 5 (insulated): a plain polythene bag blocks wind and rain but reflects nothing, a metallised bag returns most radiated heat, and a cellular bag like the Blizzard traps air as well. Retail prices change daily, so confirm on the retailer's site.
Buying guide
Mountain Rescue England and Wales, the DofE and most UK hill-walking courses list a survival bag as essential kit. Here is what separates a £5 bag from a £40 one.
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.
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.
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.
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.
How we test
Every weight, dimension and heat-retention claim on this page is taken from the manufacturer's own listing or a UK specialist retailer's spec sheet. Where listings disagree we use the manufacturer figure and say so.
Prices were last checked on 28 October 2026. We link to the cheapest in-stock UK retailer we found and list the alternatives, so you can see the spread before you click.
The thermal rating is our own 1 to 5 score. It rewards an insulating structure first, a reflective layer second, and a plain barrier last. It is not a laboratory measurement.
About
SleepGear is a developer-led gear testing and spec aggregation platform helping UK hikers, runners, and wild campers make data-driven decisions.
We care about grams, seams and hydrostatic head, not marketing copy, and we show our sources so you can check our work.