Bags rated for a Scottish winter, an alpine hut or a cold bothy floor. Compared on ISO comfort ratings, fill weight and what they cost to carry.
13 products, lightest first
9 photosWarmest lab-rated#1Alpkit
An EN-rated -10.5 °C comfort bag at under 1 kg for £350, direct from Alpkit.
From
£349.99
at Alpkit
8 photosLight winter down#2Rab
ISO comfort -5 °C from 1070 g, using 600 g of 800 FP goose down and a 10D/20D Pertex Quantum shell.
From
£484.99
at Ultralight Outdoor Gear
8 photosWarmest for weight#3Sea to Summit
850+ fill hydrophobic goose down and double draught collars: -10 °C comfort at 1.1 kg.
From
£516
at Rock+Run
Premium pick#4Cumulus
700 g of 850 FP Polish goose down in a 1.15 kg bag rated to -10 °C comfort; direct from Poland.
From
£399
at Cumulus
2 photosBest all-rounder#5Mountain Equipment
Trapezoid box-wall baffles and traceable duck down for a -6 °C comfort rating at 1.2 kg.
From
£322.12
at Alpinetrek
2 photosBest all-round winter#6Rab
Rab's workhorse winter bag: ISO -5 °C comfort with hydrophobic down.
From
£305.95
at Snow+Rock
7 photosBest value#7Alpkit
900 g of recycled RDS down and a roomy cut for under £250, direct from Alpkit.
From
£249.99
at Alpkit
9 photosExpedition#8Mountain Equipment
ME's lightest expedition bag: 831 g of 800 FP goose down, rated to -23 °C, 1490 g in total.
From
£482.44
at Trekitt
7 photosCheapest ISO winter#9Decathlon Simond
The cheapest lab-tested -5 °C bag we found. Heavy, but it shrugs off damp.
From
£79.99
at Decathlon
Best value deep cold#10Rab
ISO comfort -10 °C for £390 or less: 880 g of 650 FP hydrophobic duck down in a roomy wide mummy.
From
£347.55
at Hardloop
2 photosSynthetic winter#11Snugpak
UK-made synthetic winter bag rated to -10 °C comfort for about £160–£212, 2 kg standard size.
From
£159.99
at Dragon Supplies
6 photosBest synthetic#12Snugpak
Military-grade synthetic bag with an expansion panel and boots-on foot, rated to -15 °C by Snugpak.
From
£126.95
at John Bull Clothing
2 photosBudget winter#13Snugpak
A British-designed winter bag rated to -12 °C by Snugpak, at under £70.
From
£67.99
at Summits
Weights and sizes are manufacturer figures. Prices were checked on 31 October 2026 and change daily, so confirm on the retailer's site.
A Scottish winter camp is typically -5 to -10 °C with wind. A comfort rating of -8 °C or lower, with a good mat underneath, covers most UK winter nights.
Down gives far more warmth per gram and packs smaller. Synthetic is heavier but shrugs off a week of damp, which matters on long trips without drying time.
A sleeping bag does nothing underneath you. Pair a winter bag with a mat of R-value 4 or higher or the ground will take the heat anyway.
The warmest winter bags have an insulated collar at the neck and a baffle behind the zip. Without them, warm air escapes every time you move.
Methodology
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.
