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Big Agnes Lost Ranger 15 F Sleeping Bag

Big Agnes Lost Ranger Sleeping Bag

Big Agnes Lost Ranger 15 Sleeping Bag



The Lost Ranger 15 sleeping bag offers warmth, compressibility and the Big Agnes System design. Lightweight enough for backpacking, this down bag is made to feel more like the comforter on your bed.

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Big Agnes is one of the premier gear manufacturers in the backpacking community. However, if you’ve never seen a Big Agnes sleeping bag, you may be in for a big surprise.

Big Agnes was the first mainstream sleeping bag manufacturer to stop putting insulation into the bottom half of their sleeping bags. This can be a shocker if you’re not expecting it, but the reasoning behind this practice is quite sound: when you lie in a normal down or synthetic sleeping bag, the weight of your body compresses all of the insulation beneath you, effectively eliminating its heat trapping potential.

Recognizing this, Big Agnes shifted its focus away from just selling traditional sleeping bags to assembling complete sleep systems that combine a quilt like sleeping bag with an insulated sleeping pad like the Primaloft-filed Big Agnes Aircore, which I’ve reviewed previously on Sectionhiker.

With that background, we’re now ready to review the merits of the Big Agnes Lost Ranger 15 F which is a 3 season bag, weighing 2 lbs. 10 oz. Filled with 650 fill goose down, the Lost Ranger is much wider than most mummy style sleeping bags. With a shoulder girth of 70 in and a hip girth of 66 in, it has a semi-rectangular shape, making it good for larger people or people who like a little more space at night.

Like all Big Agnes pads, the Lost Ranger has an outer sleeve, shown below, that you slide an inflated or rigid sleeping pad into for insulation from the ground. The Ranger also has an additional pillow pocket inside the bag and at the base of the mummy hood that is convenient for holding a pillow such as the Big Agnes Primaloft-filled Air Core Pillow, which is designed for semi-rectangular bags.

Sleeping Pad Pocket
Sleeping Pad Pocket

The Lost Ranger also comes with a draft collar that cinches around the top of your chest and prevents warm air from leaking when you move around at night. In addition, extra fabric around the zippers prevents snagging.

I’m told that the Lost Ranger is one of Big Agnes’ all time bestsellers and it’s obvious why.

Disclosure: The author owns this product and purchased it using their own funds.

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  1. it is a great value! i recommend you pick one up!

  2. What do you think about the Big Agnes Zirkel SL 20° Sleeping Bag (800 Down)? I'm "between" bags in my JMT selection; a 2 lb 45 degree Kelty and a 4 lb 0 degree bag REI. The Kelty won't be warm enough and the REI is too heavy. I'm considering selling the REI bag on eBay and "investing" in the Big Agnes.

  3. Sean,

    I have the ENCAMPMENT which is BA's syn, 15 deg F, semi-mummy cut, bag.

    I think most of my issues come from the semi-mummy cut. There is just too much dead air space inside the bag.

    I found the rating to be a bit optimistic. I am a warm sleeper and this bag has only worked to just below freezing for me (~ 30 deg F) with a light base layer on.

    The BA insulated aircore pad worked well under me, I wasn't cold from the ground.

    I like the BA sleep system, because I buy into the idea that down on the bottom half of the bag is wasted weight, since it is compressed.

    The sleeve design is awesome for preventing pad slippage/movement in the night.

    PLEASE NOTE: If you sleep on your side, you can't help but exhale into the bag; that might be a concern on long winter trips.

    I don't think the syn vs down is an issue because they add more insulation to a syn bag to make up difference in the R value between the two materials. (i.e. similar to a 650 down fill bag being heavier than a 800 down fill bag for the same rating)

    I see that the ZIRKEL has the mummy cut so maybe it lives up to the 20 deg F rating, but if I was camping at 20 deg F and HAD to buy another BA bag, I would save up the extra $$ til I could buy the POMER HOIT SL. I just don't trust BA's temp rating.

    FYI – I bought my son a MARMOT bag and consider it the best value of any hiking gear I have bought. The MARMOT bag has exceeded its temp rating.

    Good luck,


  4. I agree that Marmot has a more reliable rating than BA. I live in East Texas so locally this bag will serve me well during our winters. However, I am trekking the JMT this summer so I'll need some warmth in the higher elevations. I don't think I'll be able to test it to 20 deg, but I'm sure I'll see freezing temps. I hope to report back on my field results. Thanks for your feedback.

  5. Thanks for the review and comments. I was looking at the BA bags so this was good info. Might have to look for a lower temp rating though.

  6. I have the BA Farewell 0F rated synthetic that was only good for 30F with the insulated aircore pad. I jammed an Exped-9 into it and got comfortable to 20F but BA has established a reputation for unjustifiable bag ratings so you'd do well to buy a bag rated well below what you need.

  7. I just purchased the lost ranger 15 and used it on an AT section hike with temp down to 28 degrees F according to my small thermometer. I FROZE IN THIS BAG!!! I even put my silk liner in but to no avail! I was sleeping in an AT shelter with plank floor and there was little or no wind. Maybe BA rates the bag at centigrade rather than farenheit!! DON'T BUY ONE.

  8. Retread – what type of mat were you using? I did complete the JMT w/ the Zirkel (20 degree) and the coldest it got was 29 and I slept comfortable with no problems. Cowboy camped in low 30's. I was using the BA Insumat with the bag. I like the system, I like the bag – not sure how it will sleep in actual 20 degree temps, but I like to zip my rain shell around the foot of my bag if I know I'm going to test it's low.


  9. Bring a broken record here…the Lost Ranger is the semi-mummy and the Zirkel is a mummy cut.

    I think that difference in internal dead air space goes a long way in explaining the difference in the two bags' performance.

    I think the BA concept sleep system is sound but I wish they would test the bags to the EU standard and then market them accordingly or re-design them.

  10. sean- I was using a BA insulated air core which BA according to what I have read has rated the pad to 15 degrees as well. They do recommend using another foam pad to extend the tep range however but I was well above the 15 degree rating. In my 35 plus years of all-season backpacking I have owned numerous sleeping bags/systems and agree with Tom that something needs to be done to standardize temp ratings and bring some level of scientific evidence to support the manufacturer's claims. I have returned my Lost Ranger to the vendor and will never purchase another BA I assure you.

  11. Can I use my yellow thermal rest inflatable mattress with this? Will the matteress’s mummy type shape effect the bags warmth? Thanks

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