Big Agnes
Big Agnes Anthracite -7 °C Synthetic Sleeping Bag (Regular)
Best use
- Made for
- Backpacking and wild camping
- Not for
- Bikepacking, Winter mountain
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 13.8 litres
- Winter mountain: Comfort rating -2 °C: too cold for winter nights
From the maker's stated use and the published specs.
- Summer wild camp: 4/10 UK, roughly May to September, nights above about 8 °C, sheltered pitches.
- Three-season hills: 5/10 UK hills in spring and autumn. Wind, rain, and nights near freezing.
- Winter camp: 4/10 UK winter or high ground. Below freezing, strong wind, possibly snow. Capped at 4: needs warmth 9+ (comfort -5 °C or colder).
- Weight: 5/10 How much it adds to your pack, compared with the whole market.
Comfort -2 °C, limit -8 °C (ISO 23537).
Spring to autumn nights down to about 0 °C with a decent mat
- Zip side
- Left
- Comfort
- -2 °C
- Limit
- -8 °C
- Fill
- synthetic
- Weight
- 1.25 kg (Regular)
Packed size 13.8 L, 44 cm long and 20 cm across Compare with a 2-litre bottle
About one and a half 2-litre bottles long and about twice as wide. Drawn to scale.
Where to buy
Alpinetrek £112.46 In stock. Free delivery. Shop shows list price £149.95. Free UK delivery from £85. Cheapest in-stock colour for Regular (Zirkel Alpenglow; Olive Night is £127.46).
View at shop: AlpinetrekUltralight Outdoor Gear £144.99 In stock. Free delivery. Shop shows RRP £169.99. Free UK delivery over £15.
View at shop: Ultralight Outdoor GearPrices 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 7/10How cold a night you can sleep comfortably through. 7: Better than most.
The shop copy of Big Agnes's spec table gives ISO comfort -2 °C (limit -8 °C) for the Regular, in the -4.9 to 0 °C band. The maker's figure, not re-tested, and read from one shop page only; Advnture quotes 0 °C comfort and -6 °C limit (the Long's figures), which fall in the same band. The bag is named for -7 °C, which is its limit, not a comfort figure.
Room inside
Estimate from maker's specs: maker's shoulder girth (fewer than 3 reviews about room) 4/10How much room to move, bend your knees and sleep on your side. Roomier is comfier. 4: A bit below average.
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 5/10How much it adds to your pack. 5: Does the job. Average for wild-camping gear.
Alpinetrek's copy of the Big Agnes spec table gives 1,250 g for the Regular (Ultralight Outdoor Gear lists 1,221 g), in the 1,000-1,299 g band either way. Advnture weighed it at 1.24 kg.
Packed size
From maker's figures 2/10How much room it takes in your rucksack. 2: A weak point.
No litre figure is published. Alpinetrek gives the Regular's stuff sack as 20 x 44 cm, a cylinder: 3.1416 x 10 x 10 x 44 = 13,823 cm³, so 13.8 L, in the 13 L+ band (Ultralight Outdoor Gear lists 23 x 51 cm, about 21 L, the same band). Advnture calls the pack size large.
What reviewers say (out of 10)
Ratings marked * are from reviews and are not part of the trip score. They are reviewers' scores, not our own measurements. How we score
Comfort to sleep in*
Estimate: only 1 review about comfort to sleep in (fewer than the 3 we need, so never above 8) 8/10How comfy the shape, hood and fabric feel; not the temperature rating.
1 review on comfort to sleep in, e.g. "a super-cozy and soft synthetic three season bag that’s easy to carry, a joy to sleep in".
Zip*
Estimate: only 1 review about zip (fewer than the 3 we need, so never above 8) 8/10How smoothly the zip runs without snagging.
1 review on zip, e.g. "I found I could easily open and close the zipper while wearing a pair of thinner gloves".
In short
Good for
- Spring to autumn nights down to about 0 °C with a decent mat
- Campers who want a synthetic bag that tolerates a damp tent
Strengths
- FireLine Pro Eco recycled synthetic fill with a PFAS-free water-repellent shell and lining
- Zip runs nearly the full length, so Advnture could open it out like a blanket in mild weather; its large zip loop works with thin gloves
- Advnture found it very comfortable and reliably warm, and felt the shoulder baffles held in heat
- Three lengths: Regular, Long and Wide Long (the last two fit up to 198 cm)
Weaknesses
- Heavy and bulky for backpacking: 1.25 kg and a stuff sack of about 14 L (44 x 20 cm) (Advnture calls the pack size quite large)
- The -7 °C name is the limit rating, not a comfort figure: Advnture would not take it down that cold and judged it a bag for about freezing, with a good mat
- No independent source found that tests damp performance or durability, so those scores are blank
- The -2 °C comfort figure comes from one shop's copy of the maker's table, so check it against the label
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.
ShowHide sources (4)
- Big Agnes: Anthracite 20 traditional mummy sleeping bag (product page: fill and features; its size and weight table does not load as text)
- Ultralight Outdoor Gear: Big Agnes Anthracite 20 synthetic sleeping bag (maker's spec table with ISO comfort and limit)
- Advnture: Big Agnes Anthracite 20 sleeping bag review (Regular, tested summer and autumn 2023)
- Alpinetrek: Big Agnes Anthracite 20 synthetic sleeping bag (spec table: weight, stuff sack size, fill)