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Big Agnes
Lost Dog Sleeping Bag: 0F Synthetic

5 out of 5 stars
5 Reviews
Current price: $160.96 Original price: $229.95
30% off



Why We Like The Lost Dog Sleeping Bag

If our adventures don't stop when the days get shorter, the Lost Dog Sleeping Bag keeps us warm throughout the winter. Even though this bag isn't as light as its down counterparts, we have peace of mind knowing that if a snowdrift blows into our tent, the hydrophobic fibers coupled with the water-repellent finish keeps us warm even if we get wet. We Stay even warmer by zipping the Lost Dog to another Big Agnes sleeping bag for a snugglefest after the sufferfest.


  • 0-degree sleeping bag for cold winter nights in the backcountry
  • Hydrophobic fibers protect from early-morning condensation
  • Polyester lining feels soft while also managing moisture
  • Cordlock on the hood can be cinched with one hand
  • Pad retainer fits multiple sized pads for back- or front-country use
  • Mates with other Big Agnes bags to create a backcountry bed
  • Item #BAG00F2
Responsible Collection
[face fabric] nylon, [lining] polyester
Fireline Eco (100% post-consumer recycled polyester)
Max User Height
[regular] 5ft 10in, [long] 6ft 6in
Shoulder Circumference
[regular] 69in, [long] 72in
Hip Circumference
[regular] 60in, [long] 63in
Foot Circumference
[regular] 49in, [long] 52in
Bag Length
[regular] 5ft 10in, [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
full-length zipper
Fill Weight
[regular] 2lb 8oz, [long] 3lb 1oz
Storage Sack
Stuff Sack
rip-stop polyester
Stuff Size
[regular] 10in x 21in, [long] 10in x 21in
Claimed Weight
[regular] 3lb 8oz, [long] 4lb 1oz
backpacking, weekend camping, winter camping
Manufacturer Warranty

Overall Rating

5 based on 5 ratings

Review Summary

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

April 26, 2023

Extremely effective and comfortable

I've used it several times
Size Bought:

I bought this to be my primary winter/shoulder season car camping/glamping bag. So far, I've had 1 night down to 25 F, and 3 or 4 down to about 30F and each night I was very very comfortable. This was a great purchase and has helped me stay comfortable on cold nights. I used the REI helix sleeping pad (very basic) with an R value of about 4 and it's been everything I've needed. Ignore all the people complaining about how the back has no insulation - that's by design. In regular bags, the insulation on the back of the bag is wasted weight because the insulation only works if it isn't being crushed by the weight of your body. That's why hikers who know what they're doing buy quilts and just sleep on a high R-value pad. That way all the insulation of the bag is on top and the insulation of the pad keeps your back warm. It's a very good system when used properly, just don't be a Noob and think you can use any old pad with this.

Corey M
5 out of 5 stars

January 24, 2022

Really COLD night, I was HOT.

I've used it once or twice and have initial impressions
Size Bought:
5' 7"

I paired the Lost Dog 0F with an R-4 pad and a thermolite liner in my hammock with a 20F underquilt and rain fly for top cover. With snow on the ground and the temps at 20F at 7pm, it was going to be a cold one. After settling in, I was surprised how HOT I got. I had some of the best cold weather sleep ever. My pad is longer than 72" so it had popped out of the bottom pad holding, but the cell phone pocket, pillow pocket and extra baffles around the face hole were really great added features. I may need to trade in my normal 35F bag for another Lost Dog. I was toasty well into the low teens. At 3.5lbs for the regular size, you can't beat the grams/dollar ratio.

Dennis U
5 out of 5 stars

September 25, 2021

Pad / Pad Retainer System

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

I picked up a 30 degree Lost Dog this summer. I was so impressed with the current pad / pad retainer system I updated my circa 2000 Big Agnes cold weather bag to the new system. The no-draft collar on the bag is super functional and comfy.

George W
5 out of 5 stars

October 21, 2020

Very comfortable, pad sleeve is a win

I've put it through the wringer
Size Bought:
5' 10"

I used this for the entirety of a 6 month mountaineering/climbing/sea kayaking expedition in Chilean Patagonia last year. I've never slept better in a sleeping bag. There is no insulation on the bottom (a thick insulated inflatable pad is an absolute necessity), so all the material that would normally be under you is actually on top of you, like a big thick quilt. You can toss and turn and because of the pad sleeve, the sleeping bag doesn't move with you. I'm a stomach sleeper, so this is a very good thing. I will say that there are definitely warmer 0 degree bags out there, but its nothing a liner and long underwear can't solve. Two other things: as with every 0 degree synthetic bag, it's massive, especially the long. It'll take up 20-25% of a 70L backpack. It is also a darker color than the picture shows, and the interior has no sheen, like the picture shows. (To me this is a good thing - you don't stick to the bag as much if you get sweaty.) If you're in the market for a warm and ultra-comfortable synthetic sleeping bag, this is the one.

Jonas H
5 out of 5 stars

June 22, 2020

Seems great

I've used it once or twice and have initial impressions
Size Bought:
5' 9"

This should be an awesome bag. I haven?t had a chance to use it in the field yet but have tried it out at home and it seems to be a well made and very functional sleeping bag. I ordered the long as I like to have plenty of room and this bag is just right. I will update my review after I use it in the field extensively this fall and winter.

Shane W