Big Agnes Lost Dog Review – New Sleeping Bag Series

The Big Agnes Lost Dog is a new series of four synthetic-insulated sleeping bags with various temperature ratings so they cover all the seasons. Please keep reading.

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Lost Dog Sleeping Bags Series – Common Features

• All of the bags are built in at least two sizes, regular (R) and long (L). It appears that currently, the 15-degree bag is available in the wide-long (WL) version as well.
• These are sleeping bags with synthetic insulation. This is what they call the FireLine ECO Synthetic Insulation, i.e., 100% post-consumer recycled polyester. This insulation features low-denier fibers that are tightly woven and provide high loft, compressibility, high weight-to-warmth ratio, and durability. Such a synthetic insulation performs better than down in wet conditions, it keeps insulating you even when wet and it dries faster than down. But it is also heavier than down of course.
• The shell is a nylon ripstop fabric with a water repellent finish, and the lining is polyester.
• All the bags have inner loops for extra layering and outer loops for hanging to dry and to store.
• All of them also include a Flex Pad Sleeve – this is a stretch construction that can accommodate multiple pad widths, see the picture. The idea behind such a design is to have the pad so that it keeps the sleeping bag in place and it will not twist when you turn around during the night. Note also that bags’ insulation is lighter on the bottom of the bags, and this is because a pressed insulation has less trapped air and its insulation is not great in any case. This is compensated by the pad in the sleeve.
• All the bags have a pillow pocket.
• The 45-degrees bag is very different from the rest, this is almost a rectangular style bag and it is without the hood. The other three bags are mummy style and all have the hood.
• The zippers are the best what you can expect, anti-snag YKK #5 with the following specifications:
  – Regular: 65 in (165 cm).
  – Wide Long, Long: 70 in (178 cm).
• Height fit for all of them:
  – R: 5’10” (178 cm).
  – L: 6′ 6″ (198 cm).

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Below are some specifications for all of them, please have a look. Having these specifications in one place might be useful to decide which to use and where. The temperature rating determines the differences in weight and packed size, so by choosing the right bag you can save a lot of weight and volume in your backpack.

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1. Big Agnes Lost Dog 0 Degree Sleeping Bag

Specifications

• Temperature rating: 0 F (-18 C).
• Weight:
  – R: 4 lb 2 oz (1.87 kg).
  – L: 4 lb 10 oz (2.10 kg).
• Fill weight:
  – R: 46 oz (1.30 kg).
  – L: 52 oz (1.47 kg).
• Compressed bag size:
  – R: 11.5 x 9 in (29 x 23 cm).
  – L: 12.5 x 9 in (32 x 23 cm).
• Stuff sack size: 21 x 10 in (53 x 25 cm).
• Girth (shoulders/hips/knees):
  – R: 69/60/49 in (175/152/125 cm).
  – L: 72/63/52 in (183/160/132 cm).

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2. Big Agnes Lost Dog 15 Degree Sleeping Bag

Specifications

• Temperature rating: 0 F (-9 C).
• Weight:
  – R: 3 lb 3 oz (1.45 kg).
  – L: 3 lb 10 oz (1.64 kg).
  – WL: 4 lb (1.81 kg).
• Fill weight:
  – R: 31 oz (878 g).
  – L: 35 oz (992 g).
  – WL: 40 oz (1.13 kg).
• Compressed bag size:
  – R: 9.5 x 8 in (24 x 20 cm).
  – L: 10.5 x 8 in (27 x 20 cm).
  – WL: 12.5 x 9 in (32 x 23 cm).
• Stuff sack size:
  – R, L: 20 x 9 in (51 x 23 cm).
  – WL: 21 x 10 in (53 x 25 cm).
• Girth (shoulders/hips/knees):
  – R: 69/60/49 in (175/152/125 cm).
  – L: 72/63/52 in (183/160/132 cm).
  – WL: 80/71/60 in (203/180/152 cm).

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3. Big Agnes Lost Dog 30 Degree Sleeping Bag

Specifications

• Temperature rating: 0 F (-1 C).
• Weight:
  – R: 3 lb (1.36 kg).
  – L: 3 lb 6 oz (1.53 kg).
• Fill weight:
  – R: 26 oz (737 g).
  – L: 30 oz (850 kg).
• Compressed bag size:
  – R: 8.5 x 7 in (22 x 18 cm).
  – L: 9.5 x 7 in (24 x 18 cm).
• Stuff sack size: 17.5 x 8 in (45 x 20 cm).
• Girth (shoulders/hips/knees):
  – R: 69/60/49 in (175/152/125 cm).
  – L: 72/63/52 in (183/160/132 cm).

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4. Big Agnes Lost Dog 45 Degree Sleeping Bag

Specifications

• Temperature rating: 45 F (7 C).
• Weight:
  – R: 1 lb 12 oz (794 g).
  – L: 1 lb 15 oz (879 g).
• Fill weight:
  – R: 10 oz (283 g).
  – L: 12 oz (340 kg).
• Compressed bag size:
  – R: 6.5 x 5.5 in (17 x 14 cm).
  – L: 6.5 x 6.5 in (17 x 17 cm).
• Stuff sack size: 15 x 7.5 in (38 x 19 cm).
• Girth (shoulders/hips/knees):
  – R: 69/60/49 in (175/152/125 cm).
  – L: 72/63/52 in (183/160/132 cm).

Please see more about all of them in this short video:

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Synthetic Insulation vs Down Insulation – the Weight Difference That Matters

So these bags are with synthetic insulation and for such a type they are lightweight. You will hardly find anything lighter and better packable. Synthetic insulation performs better in wet conditions than down, but the modern down fill is normally treated and the difference in performance is not big in general. But the weight difference can be substantial. Here are some examples to demonstrate this.

Big Agnes Lost Dog 0 vs Therm-a-Rest Oberon 0 Degree

• Therm-a-Rest Oberon 0 Degree R: weight 1110 g.
• Big Agnes Lost Dog 0 Degree R: weight 1870 g.

Here, the weight ratio between the two bags is 0.59. The Therm-a-Rest bag is with Nikwax 800 Down fill and it is EN rated.

Big Agnes Lost Dog 15 vs Big Agnes Mystic 15 

This Mystic 15 sleeping bag is with the same temperature rating but here you have 850 DownTek fill. Both are built in the mummy style and both have the sleeve for the pad. See the weights side by side:

• Big Agnes Mystic 15 R: weight 907 g; fill weight 397 g.
• Big Agnes Lost Dog 15 R: weight 1450 g; fill weight 878 g.

So the weight ratio between the two bags is around 0.63. But see yet another example for the 30-degree temperature rating:

Big Agnes Lost Dog 30 vs Big Agnes Flume 30

• Big Agnes Flume 30 R: weight 624 g; fill weight 340 g.
• Big Agnes Lost Dog 30 R: weight 1360 g; fill weight 737 g.

Note that the Flume 30 bag is with 850 down fill and it is EN rated. So the weight ratio is around 0.46, i.e., the down-fill bag is less than half the weight of the synthetic insulated bag, this is remarkable.

So now you can realize why these down fill bags are so expensive. Note also that they are usually far more packable.

Thank you for reading. Please use the comment box below in the case of questions or comments. Have a nice day.