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Sierra Designs Vapor 15 Sleeping Bag Review

850 fill power down, 15 F temperature rating, 30 ounces – the lightest 15-degree mummy style sleeping bag to be found.


Overall Rating: Recommended

The Vapor 15 is simple, lightweight, and warm – just the way we like it. It does not have the partial flex technology and zippered foot vent found on other bags in the Sierra Designs Ultralight Series, the shell and lining fabric are lighter, and the down quality is bumped up to 850 fill power to create the lightest 15 degree rated down mummy bag to be found. It clearly deserves our Recommended rating, but falls short of our highest rating due to its heavier zipper track, short sizing, and lack of a neck baffle.

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by Will Rietveld |


Sierra Designs Vapor 15 Sleeping Bag Review - 1
The new Vapor 15 sleeping bag raises the bar (for Sierra Designs) to 850 fill power down, and has a new 15 denier nylon shell and lining fabric. The unisex bag is available in sizes Short, Regular, and Long.

For the shoulder seasons and for some winter camping situations, many hikers prefer to use a sleeping bag with a temperature rating of 10-20 F (-12 to -7 C). Others may prefer a warmer bag like this for summer backpacking in the mountains, simply to ensure they don’t get cold. While the latter group could benefit from our lightweight philosophy, as explained for sleeping bags in our article: Ultralight Three-Season Down Mummy-Style Sleeping Bags: State of the Market Report 2010, both groups can save weight by carrying an ultralight sleeping bag.

Sierra Designs claims their Vapor 15 is the lightest 15 degree down mummy-style sleeping bag on the market (we will check that out in this review). The Vapor 15 sets another landmark for Sierra Designs - their first bag featuring 850 fill power down - rivaling bags from Marmot, Feathered Friends, and Western Mountaineering. What is there to like and dislike about the new Vapor 15, and how does it stack up, by the numbers, to comparable bags?


As a departure from other bags in Sierra Designs Ultralight Series, the Vapor 15 raises the bar to 850 fill power down. It has the same Jacket Hood and half-length (25 in/64 cm) zipper as other bags in this series, but it does not have the Sierra Designs Flex Technology used in the other bags. Also missing is a footbox zipper - I guess they assume that most users will want to retain heat in a 15 F (-9.4 C) rated bag.

Sierra Designs Vapor 15 Sleeping Bag Review - 2
The unisex Vapor 15 is a member of the Sierra Designs Ultralight Series of bags that feature a unique jacket-style hood and a half-length zipper.

The 15 denier nylon shell and lining fabric used in the Vapor 15 are lighter and more durable than the 22 denier ripstop polyester used in other bags in the Sierra Designs Ultralight Series.

Although the Vapor 15 does not have a women’s version, it does come in a size Short that fits people to 5 feet 6 inches (1.7 m). It also comes in size Regular that fits people to 6 feet (1.6 m), and Long that fits to 6 feet 6 inches (2 m) (read my issue on sizing in the Performance section).

Sierra Designs Vapor 15 Sleeping Bag Review - 3
All Sierra Designs bags feature a Snag-Free Zipper Track to prevent zipper snags. The key component is a stiff piping on both sides of the zipper that creates a barrier between the bag’s lining and the zipper track. The bag also has a large down-filled draft tube on the bottom side of the zipper to prevent cold spots.

Sierra Designs Vapor 15 Sleeping Bag Review - 4
The Vapor 15 has Sierra Designs unique Jacket Hood (left), which is exactly what it says - it looks and fits like the hood on a down parka, and it’s well insulated. The bag’s zipper angles from the side to the base of the hood. The hood draws down like a sleeping bag hood to expose only your nose and mouth (right).

Sierra Designs Vapor 15 Sleeping Bag Review - 5
The Vapor 15’s footbox is anatomically shaped to provide extra room for big feet like mine, or for wearing down booties inside the bag. There are two removable Pad Locks (thin straps that pass through loops on the bag) to attach the bag to a sleeping pad (right) to prevent slide off.


Sierra Designs Vapor 15 Sleeping Bag Review - 6
Winter camping using the Vapor 15 bag inside an igloo at 9,500 feet (2,896 m) elevation on a cold February night.

For convenience, in February and March I tested the Vapor 15 in a single-wall tent set up in my back yard in an area where I shoveled away the 2-foot (61 cm) snowpack. Temperatures during seven nights of testing ranged from 27 to 12 F (-3 to -11 C). I also tested the bag in my igloo at 9,500 feet (2,896 m) on one late February night where the temperate got down to 23 F (-5 C). In the spring I used it on an April six-day backpacking trip in southern Utah where the nighttime temperatures ranged from 25 to 52 F (-4 to 11 C), and one late spring alpine backpacking trip where I slept between snowdrifts and the temperature dropped down to 18 F (-10 C).

The amount of 850 down fill in the Vapor 15 is 16, 18, and 20 ounces (454, 510, 567 g), respectively, for the Short, Regular, and Long lengths. I tested the Vapor 15 in a size Long, and measured the two-layer loft at 6 inches/15 centimeters (single-layer loft is 3 in/7.6 cm). Additionally, the bag has continuous baffles, so it’s possible to shift more of the down to the topside, if desired. According to our table of estimated temperature ratings based on measured loft (read our Backpacking Light Position Statement on Sleeping Bag Temperature Ratings, 3 inches (7.6 cm) of single-layer loft translates to a 0 F (-18 C) rating, so on a loft basis it appears that the Vapor 15 is conservatively rated. Please read the referenced article and Ryan Jordan’s article entitled Sleeping by Faith: Bag Temperature Ratings and realize that sleeping bag warmth depends on a number of factors.

Sierra Designs Vapor 15 Sleeping Bag Review - 7
Verification that the Vapor 15’s double-layer loft (left) measures 6 inches (15 cm). A lightweight (0.6 ounce/17 g) stuff sack is provided with the Vapor 15 that is properly sized to stuff the bag without over-compressing it. Actually, it’s a little extra roomy, which I don’t mind a bit.

One important issue is sizing: Sierra Designs bags apparently run short. In my previous review of the Sierra Designs Nitro 30 sleeping bag, I found that size Regular did not fit a person up to 6 feet (1.8 m) as claimed. I found it too short, and my height is exactly 6 feet (1.8 m). Size Regular will fit people up to 5 feet 10 inches (1.8 m) at the most. In testing the Vapor 15, I wisely opted for the Long length and found it much more to my liking in terms of length as well as girth. In fact, size Long is just right for my height; it can accommodate a person up to 6 feet 2 inches (1.9 m), but it would be too short for anyone taller than that. The bag has adequate girth in the shoulder and hip areas to wear a puffy down jacket and down pants inside without being too tight.

It’s hard to design a sleeping bag zipper track that is lightweight and snag-free. Sierra Designs Snag-Free Zipper Track does minimize snagging, but it adds significant weight to the bag. The heavy-duty zipper track is apparently needed because the zipper curves across the chest area to the base of the Jacket Hood. I personally did not mind the half-length (25 in/64 cm) zipper on the Vapor 15. It makes it a little more cumbersome to get into and out of the bag, but I found it easy to adjust. However, the short zipper excludes the option to zip two bags together or to open the bag up and use it as a blanket on warmer nights.

So, how warm is the Vapor 15? In my testing, I wore only a microfleece top, bottom, and cap inside the bag so I could determine the bag’s actual warmth. I kept a down jacket and pants next to me that I could put on if I got cold. That happened only once, when the temperature dropped down to 12 F (-11 C). After I donned the extra clothing, I stayed nice and warm the rest of the night. On another night when the temperature dropped to 18 F (-10 C), I started getting a little chilly, but not enough to add clothing. I didn’t have the opportunity to test the bag in serious winter camping conditions, but from my testing experience I believe I can extend the warmth of the Vapor 15 down into the single digits by wearing a down jacket, pants, and booties inside. Overall, in my opinion the Vapor 15’s temperature rating is slightly optimistic, which is typical in U.S. made sleeping bags.

The bag’s draft tube along the zipper is on the bottom side, rather than the top side on most bags. It seems logical to place it on the top side so gravity will help hold it in place. During my testing, I specifically checked the draft tube to see if it was sealing the zipper, and found that it was. The curved zipper design seems to necessitate putting the draft tube on the bottomside to avoid snagging, and the curved zipper does keep the draft tube in its proper place. It should also be noted that the Vapor 15 does not have a neck baffle at the base of the hood, as do many bags in this temperature range.

I tested the bag’s water resistance with my “puddle test,” where I put 1/8-cup of water on a seam and allowed it to stand for one hour. No water soaked through the seam or fabric, indicating the fabric is very water resistant and the seams are tight.

The bag’s pad attachment straps are useful for a back sleeper or hammock sleeper. But I’m a side sleeper, so I had no use for the straps because I want the bag to turn with me. The pad straps are easy to remove and reduce bag weight by 0.5 ounce (14 g), down to 30.4 ounces (862 g) for size Long.


The following table compares the Sierra Designs Vapor 15 with some popular 10-20 F (-12 to -7 C) rated ultralight mummy style down sleeping bags. All of the bags have continuous baffles, and all data are manufacturer specifications for a size Regular bag.

Manufacturer Model Temperature Rating (F/C) Single-Layer Loft (in/cm) Fill Weight (oz/cm) Fill Power Total Weight (oz/g) Cost US$
Sierra Designs Vapor 15 15/-9.4 3.0/7.6 18/510 850 30/850 440
Western Mountaineering Versalite 10/-12 3.0/7.6 20/567 850 32/907 440
Feathered Friends Raven 10/-12 3.0/7.6 20/567 850 37/1049 420
Marmot Helium 15/-9.4 na 19.5/553 850 34/964 369
MontBell UL Spiral Down Hugger #1 15/-9.4 na 20/567 800 32/907 329

As you can see from the data, Sierra Designs can reasonably claim that their Vapor 15 is, in fact, the lightest 15 degree bag to be found. However, the comparison is complicated by the different temperature ratings assigned to the bags. The Marmot Helium bag has 1.5 ounces (43 g) more down than the Vapor 15, and has an EN tested temperature rating of 15 F (-9.4 C), which further supports my observation that the Vapor 15’s temperature rating is a bit optimistic. The Marmot Helium is a better value than the other bags listed, and it has a full-length zipper, but its shell fabric is heavier and not as water resistant as the other bags. The MontBell UL Spiral Down Hugger #1 has 800 fill power down, is almost as light as the Vapor 15, and costs $91 less. It has a 2/3-length zipper, soft 12 denier shell and lining fabric, and its Polkatex DWR is superb.


I have not personally tested any of the other 10-20 F (-12 to -7 C) rated bags in the table above, so I can’t compare them other than by the numbers. One main difference is the Vapor 15 has a half-length zipper, while the others all have a full-length zipper. Many hikers would not have a bag that doesn’t have a full-length zipper, but personally the half-length zipper is no problem for me. I need the warmth on most of the trips where I would take a 15-degree bag, so I rarely have the problem of overheating. Another reason for the half-length zipper is the bag’s Jacket Hood, which necessitates the curve in the zipper to the base of the hood, which in turn necessitates the heavy-duty zipper track for smooth operation and minimal snagging. A full-length zipper of that design would add too much weight.

Overall, I really like the Vapor 15. It provides plenty of warmth for its sub-2-pound (907 g) weight. It weighs about the same as many bags rated at 20-25 F (-7 to -4 C) and is significantly warmer. Its just right for mountain backpacking in the shoulder seasons (late spring and fall), certain winter camping situations by wearing extra clothing inside the bag as needed, and for cold sleepers who want to ensure they stay warm.

When choosing a Sierra Designs bag, it’s very important to know that the sizing runs short, at least that is my experience from the two bags I have recently tested. A size Regular bag from most manufacturers, sized to fit a 6 foot (1.8 m) tall person, normally fits me just fine, and I am 6 feet tall. Not so with a Sierra Designs bag. I found a size Regular to be uncomfortably short, but a size Long fits great. I don’t have any information on the sizing of the size Short bag, but I note that getting a size Short sleeping bag is a good approach for a shorter person to reduce pack weight.

Other than the length issue, I did not find any problems with the Vapor 15. It’s simple, lightweight, and warm - just the way I like it.

Specifications and Features

Manufacturer Sierra Designs (
Year/Model 2010 Vapor 15
Style Hooded mummy with ½-length left side zipper
What’s Included Sleeping bag, stuff sack, cotton storage bag
Fill 850 fill power down, 16 oz (454 g) size Short, 18 oz (510 g) size Regular, 20 oz (567 g) size Long
Construction 5.5 in (14 cm) straight wall continuous baffles, ergonomically shaped footbox, six chamber jacket hood
Measured Loft 6 in (15 cm) average double-layer loft, 3 in (7.6 cm) single-layer loft
Manufacturer specification not available
Manufacturer Claimed Temperature Rating 15 F (-9.4 C)
Stuffed Size 18 x 8 in (46 x 20 cm)
Weight Size Long tested
Measured Weight: 1 lb 14.9 oz (876 g)
Manufacturer Specification: 1 lb 14 oz (850 g) size Regular
Dimensions Shoulder/hip/foot
Short: 54/48/35 in (137/122/89 cm)
Regular: 57/50/37 in (145/127/94 cm)
Long: 60/52/39 in (152/132/99 cm)
Sizes Short fits to 5 ft 6 in (178 cm)
Regular fits to 6 ft (183 cm)
Long fits to 6 ft 6 in (188 cm)
See my comments in the review.
Fabrics Shell and lining are 15 denier 0.76 oz/yd2 (26 g/m2) ripstop nylon with DWR
Features ½-length zipper with 1 pull, snag-free zipper track, anatomical footbox, continuous baffles, large down-filled draft tube, jacket hood, 2 pad straps
MSRP Short US$420, Regular US$440, Long US$460

Disclosure: The manufacturer provided this product to the author and/or Backpacking Light at no charge, and it is owned by the author/BPL. The author/Backpacking Light has no obligation to review this product to the manufacturer under the terms of this agreement.


"Sierra Designs Vapor 15 Sleeping Bag Review," by Will Rietveld. (ISSN 1537-0364)., 2010-08-24 00:00:00-06.


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Sierra Designs Vapor 15 Sleeping Bag Review
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Addie Bedford
(addiebedford) - MLife

Locale: Montana
Sierra Designs Vapor 15 Sleeping Bag Review on 08/24/2010 15:05:29 MDT Print View

Companion forum thread to:

Sierra Designs Vapor 15 Sleeping Bag Review

Kathy A Handyside
(earlymusicus) - M

Locale: Southeastern Michigan
Sierra Designs Vapor 15 on 08/24/2010 15:33:05 MDT Print View

A very thorough review. However, I'm a side-sleeper and a restless sleeper. I need a bag that has some flex to avoid feeling like I'm being held hostage in my sleeping bag. If this bag had the Sierra Designs flex, I might consider it. I will continue to save up for a Mont Bell Super Spiral down hugger bag instead.

Arapiles .
(Arapiles) - M

Locale: Melbourne
Re: Sierra Designs Vapor 15 - metric measurements on 08/25/2010 22:49:56 MDT Print View

Something seems to have gone awry with your metric conversions: a centimetre is approximately 2.54 cm therefore;

5'10" = 177.8 cm (usually rounded to 178 cm, not 180/1.8m)

6' = 182.88 cm (usually rounded to 183 cm, not 180/1.8m)

6'2" = 187.96 cm (usually rounded to 188 cm, not 190/1.9m)

Edited by Arapiles on 08/25/2010 22:55:14 MDT.

Ronald Feltner
(ronfel49) - F

Locale: Indiana
Zipper comment on 08/28/2010 16:25:00 MDT Print View

"I have not personally tested any of the other 10-20 F (-12 to -7 C) rated bags in the table above, so I can’t compare them other than by the numbers. One main difference is the Vapor 15 has a half-length zipper, while the others all have a full-length zipper"

The WM Versalite also has a half-length zipper.

Jim Sweeney
(swimjay) - MLife

Locale: Northern California
Bag length on 08/30/2010 21:27:49 MDT Print View

Thanks for the excellent review, Will. It's great to see another manufacturer moving further in the direction of ultralight, high quality gear.

In discussions of bag length, I don't think I've ever seen acknowledgment of the importance of foot length, and ankle extension. A person with a longer foot, and a looser ankle, will have an overall body length considerably longer, when lying on their back, then someone with a shorter foot or a "stiffer" ankle. So in a shorter bag, a longer-footed person will more easily have the feeling that the bag is too short, as they feel their toes pressing agains the foot of the bag, and their head against the hood. I've never done the research, but I'll bet the difference between a stiff-ankled size 9 foot and a loose ankled size 11 foot could be easily two inches.

Another thing to note, though I haven't seen the Vapor, is that the Marmot helium is, as I remember, generously cut (i.e, large cross-sectional diameter), and the vapor looks more compact, judging from the photos. So the average down density per square inch of bag surface, which is, I think, more important than the total down in a bag, might favor the Vapor.

Misfit Mystic

Locale: "Grand Canyon of the East"
WM zipper on 08/31/2010 07:25:53 MDT Print View

The zipper on the WM Versalite is definitely full-length, as it is on all their bags other than the Highlite. Considering the Vapor 15 is essentially the same price ($440 for the SD, $455 for the WM) I believe the Versalite is a much better value. It's performance is legendary in this community.

Chris W
(simplespirit) - MLife

Locale: .
Re: WM zipper on 08/31/2010 07:32:42 MDT Print View

Yup, Versalite has a full length zip. I believe it's an MSRP of $440 though for regular length. Of course, you're far more likely to find a deal on the SD bag for what that's worth.