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Big Agnes
Lost Dog Sleeping Bag: 15F Synthetic

4 out of 5 stars
4 Reviews
$199.95 - $219.95



Why We Like The Lost Dog Sleeping Bag

Instead of packing up the camp gear when the temps drop, add the 15-degree Lost Dog Sleeping Bag to your kit for warmth on winter nights. Whether we're hiking into a snow-capped cirque or skinning to a backcountry yurt the Lost Dog won't weigh us down while keeping us warm. Between the pillow barn and the low-profile cordlock hood, we stay cozy and comfortable while the no-draft collar keeps that pesky cold air from creeping inside. And the inside is lined with soft polyester to maintain the hydrophobic nature of the bag while also feeling soft against the skin.


  • 15-degree sleeping bag for moderate winter nights
  • Pad retainer works with multiple widths for back- and front-country use
  • Jacket-style hood fits the shape of your face for a more comfortable fit
  • Mates with other Big Agnes bags to create a backcountry bed
  • Water-repellent finish combined with synthetic fill creates hydrophobic bag
  • Free-range foot-box makes more room for your feet
  • Item #BAG00F1
[face fabric] nylon, [lining] polyester
FireLine ECO synthetic
full-length YKK anti-snag
Max User Height
[regular] 5ft 10in, [long] 6ft 6in, [wide long] 6ft 6in
Shoulder Circumference
[regular] 69in, [long] 72in, [wide long] 80in
Hip Circumference
[regular] 60in, [long] 63in, [wide long] 71in
Foot Circumference
[regular] 49in, [long] 52in, [wide long] 60in
Bag Length
[regular] 5ft 10in, [long] 6ft 6in, [wide long] 6ft 6in
Draft Tube
no-draft collar, no-draft wedge, no-draft zipper
Pad Retainer
[regular] 20in-25in x 72in, [long] 20in-25in x 78in, [wide long] 25in-30in x 78in
full-length zipper
Fill Weight
[regular] 1lb 9oz, [long] 1lb 12oz, [wide long] 2lb 1oz
Storage Sack
Stuff Sack
polyester rip-stop
Stuff Size
[regular] 9in x 20in, [long] 9in x 20in, [wide long] 10in x 21in
Claimed Weight
[regular] 3lb 3oz, [long] 3lb 10oz, [wide long] 4lb
Manufacturer Warranty

Overall Rating

4 based on 4 ratings

Review Summary

1 Stars - 1 reviews
2 Stars - 0 reviews
3 Stars - 0 reviews
4 Stars - 0 reviews
5 Stars - 3 reviews

Fits True To Size

Screen reader users: the following list provides a visual scale to illustrate the product fit. Please refer to the heading above for the fit type in text.
Runs smallTrue to sizeRuns large

What do you think about this product?


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5 out of 5 stars

December 31, 2021

Great bag for tall people

I've used it once or twice and have initial impressions
Size Bought:
6' 5"

I am a tall guy 6?5? and was in need of a longer bag. It suited that task and is advertised as a long bag. Long and warm. Should mention I took it out camping and had it paired up with a ?non-insulated? air mattress from the same brand. It was warm enough to not disturb my rest but it did diminish its overall warmth. If you?re gonna camp in the cold, do yourself a favor and get an insulated mattress.

Graham S
5 out of 5 stars

August 27, 2021

Excellent Bag For The $$

I've used it several times
Size Bought:
Wide long Left Zip.
6' 2"

I've used this bag several times in the Colorado Rockies. Haven't used it in too cold of weather yet? But sure it will be fine? I have to get a different pad as mine does not fit in the slot. Otherwise it works great! Very roomy and comfy for me. I'm a big guy. Note: My only complaint is it dosen't come with a stuff/compression sack as my marmot bag did. So I had to get one for it. No big deal. I highly recommend this bag!! My marmot bag is very nice, but a little too snug for my liking. This gives me the room I like!!! If your a bigger person and like the extra room, THIS IS YOUR BAG!! BUY IT!

Brian V
5 out of 5 stars

July 12, 2021

Love this bag

I've used it several times
Size Bought:
Wide Long
6' 1"

This bag is my favorite piece of backpacking gear. I used it with the big agnes q-core (blue) and slept like a baby for 4 nights in the Chicago Basin with lows in the high 30s to low 40s. I got more sleep per night backpacking than I have in years at home in bed. I've also used it in the spring with the neoair uberlite waking up to high-20s. I have been very warm in this thing and have rarely needed to zip it up completely. I would definitely buy another lost-dog bag in the future if needed.

Brian E
1 out of 5 stars

July 1, 2021


Size Bought:
men's long

Be sure you are aware that this REQUIRES the sleeping pad - THERE IS *NO* FILL ON THE UNDERSIDE!! I noticed when looking at it online that it has an elastic "pad retainer" and thought it might work with our Thermarest, or we would just not use it, either way would be fine -- I did not see until it shipped to my home that it is a system with NON-OPTIONAL components. The website does not clearly illustrate or describe the situation. It says "Pad retainer works with multiple widths..." IT DOES NOT SAY YOU *HAVE* TO GET THE PAD AND THAT IT'S SOLD SEPARATELY!! I thought I'd found the perfect bag for my long tall son who doesn't like the constrictive feel of a standard mummy bag, and I would have him give it a try except that my husband and I have really good 0 degree (shout out to Marmot) bags (with fronts and backs included!) + good Thermarest pads and we are not overly warm where we camp, so why would our son be warm on a pad in a bag that is 1/2 polyester sheeting??

Salal R