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Therm-a-Rest Vesper 45 Ultralight Backpacking Quilt Review

 Therm-a-rest Vesper 45 Ultralight Quilt Review
The Therm-a-Rest Vesper 45 Ultralight Quilt is a 12 oz warm-weather quilt with premium materials and impressive performance features for the weight like a draft collar, pad attachment, shaped footbox, and wide girth. It’s exciting to see such a high level of quality in an off-the-shelf quilt compared to the custom-made quilts used by many backpackers.

Specs at a Glance

We tested the Regular version; there is also a Long version (which is also three inches wider).

  • Quilt Weight (manufacturer’s): 12 oz / 0.34 kg; (we measured 12.4 oz w/pad attachment strap)
  • Compression stuff sack weight (tested): 1.4 oz. / 0.04 kg
  • Width 58” / 147 cm
  • Length: 75” /190.5 cm
  • Shoulder girth: 58” / 147.32 cm
  • Hip girth: 51” / 129.54 cm
  • Footbox girth: 37” / 93.98 cm
  • Fits a person up to 72” (6 feet) / 1.83 meters
  • Packed size: 4.5”x 6” (in compression sack) / 11.43 cm x 15.24 cm
  • Down Fill: 6 oz. (0.18 kg) of 900 Fill Goose Nikwax Hydrophobic Down, RDS (Responsible Down Standard) certified
  • Shell material: 10 D (denier) nylon ripstop with DWR (Durable Water Repellent)
  • Lining material: 10 D nylon ripstop

Therm-a-Rest Vesper 45 Quilt

Insulation Value
Shell and Liner
Pad Attachment System

Insanely Lightweight

The Therm-a-Rest Vesper 45 Quilt is a high-quality, ultralight, and ultracompact quilt that I found to be true to its temperature rating. It’s a great warmer-weather option for backpackers and fastpackers looking to minimize weight and bulk from their kit without minimizing features.

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Temperature Rating

The most common question asked about a sleeping bag or quilt is “Will this keep me warm at X temperature?” The ISO/EN rated temperature range, the industry standard for measuring sleeping bag warmth, is printed right on the bag: 45 degrees is the Lower Limit and 52 degrees is the Comfort rating. I’m a cold sleeper who usually adds a few degrees to the stated temp rating of insulation, yet I found this rating to be spot on or even a bit conservative. Wearing just long, lightweight baselayers, at 50-55 degrees in this quilt, I was warm and cozy. At 45 degrees I was cool but could still sleep comfortably. I’ve taken this quilt down to 38 degrees and between that temp and 42 degrees I needed to supplement my insulation. The loft is impressive for such a lightweight quilt.

The Vesper 45 is very lofty for such a light quilt--you can tell I don’t want to get up.
The Vesper 45 is very lofty for such a light quilt–you can tell I don’t want to get up.

Premium Materials and Design

The Vesper 45 is one of Therm-a-Rest’s ultralight series of quilts. Besides the 45 degrees version we tested, they also offer a Vesper 32 Quilt and a Vesper 20 Quilt. The 45 degrees quilt is a sewn-through baffle design, while the warmer quilts are box-baffled to eliminate cold spots. However, I found the 45-degree quilt so lofty for its weight, that I didn’t feel the sewn-through areas as cold spots when it was used within its recommended temp range.

All of the Vesper quilts use 900 fill power water-resistant down which has been RDS (Responsible Down Standard) certified to never come from birds that have been force-fed or live-plucked. Its shell and liner fabrics are both 10 denier nylon fabrics that are soft and silky. 10 denier is a more delicate fabric, but a sleeping quilt is a smart place to use this kind of fabric for weight savings.

There are ultralight quilts on the market which save weight with minimal features, but the Vesper manages to keep a 12 ounce weight while maintaining a bunch of features found on much heavier quilts. That’s pretty incredible.

The neck has a draft tube which closes with a snap, and cinches with a drawcord, trapping heat in.
The neck has a draft tube that closes with a snap, and cinches with a drawcord, trapping heat in.

Neck Cinch and Draft-collar

There is a single snap at the neck of the quilt, and a thin drawcord with mini captured cordlock offset from the center to cinch the quilt around your neck. Surprisingly for a quilt of this weight, there is a draft collar at the neck. This helps keep the heat in and is much more comfortable around your neck than a drawcord in an uninsulated fabric tube; with the draft collar you don’t have to cinch the cord as tightly.

Box-shaped Footbox and U-cutout

The Vesper is a sewn-end quilt with a box-shaped footbox that allows the toes of back sleepers to point upwards without being cramped. When you flip the quilt over, the closed footbox opens up to the opening of the quilt with a gentle U-shape. On many quilts, the footbox opens up into a V along a seam, which puts lots of stress at the point of that V and often requires a gusset or other reinforcement to keep the fabric from ripping when you kick your feet in and out. The U-cutout of the Vesper quilt spreads the tension along a much greater area, and not on a seam.

Wide Shoulder Girth

The Vesper 45 quilt is 58” wide at the shoulders, which is wider than many companies’ wide quilts! It tapers down from there to 51” at the hips, and then 37” at the feet. This wide shoulder girth allows you to get great coverage around your torso with room to tuck it under you. I move between my stomach and side sleeping in the night, and I really appreciated this extra girth as I changed positions. This extra width also reduces the quilt’s dependence on a more cumbersome sleeping pad attachment system, since the quilt’s extra width blocks side drafts quite effectively. 

The Vesper 45 has down-filled draft tubes running along the sides of its opening to keep heat in.
The Vesper 45 has down-filled draft tubes running along the sides of its opening to keep heat in.

Side Draft Tubes

While the quilt does taper down from the wide shoulder girth, it has draft tubes built into the sides that create a barrier for drafts when the quilt is on top of you, and can also be tucked underneath you for more secure draft protection.

SynergyLink Pad Connector Strap

The Vesper 45 comes with a single pad connector strap called a SynergyLink which is a simple elastic strap that goes around a sleeping pad with no adjustability. Thin plastic toggles hook into tiny loops on either side of the quilt, in one of two positions, closer to the chest or closer to the waist. The strap connects not at the very edge of the quilt but rather above the side draft tubes so the draft tubes can tuck in around you.

The SynergyLink pad connector is an elastic strap that toggles into tiny loops at the waist or chest.
The SynergyLink pad connector is an elastic strap that toggles into tiny loops at the waist or chest.

My first instinct was to use the higher loops (the ones closer to the chest) as there is more quilt to cinch in that area. But I found I vastly preferred connecting the strap at the lower level. When it was connected in the higher position around the sleeping pad, I found that I could no longer snug the quilt tightly around me, one of the best features of a quilt, as it was pinned down to the sides of the pad.

The simple elastic pad connector is low profile and fits between the chambers of an air mattress.
The simple elastic pad connector is low profile and fits between the chambers of an air mattress.

When I connected the strap to the lower level, it was easier to get into and out of the quilt in the night, and kept the quilt tucked into place around my knees. Using the strap at the lower level also allowed me to vary the degree to which I draped or tucked the quilt around the upper part of my body, the feature I had missed in the other position. I’ve used the strap ever since in the lower position, sometimes around a pad, sometimes around my body, and find both of these options work well.

Comparable Off-the-Shelf Warm-Weather Backpacking Quilts

Make / ModelWeight
Therm-a-Rest Vesper 2019 oz
Therm-a-Rest Vesper 3215 oz
Therm-a-Rest Vesper 4512 oz
Hyperlite Mountain Gear 2020.1 oz
Hyperlite Mountain Gear 4014.4 oz
REI Magma Trail 3019 oz
Sea to Summit Cinder 5016.9 oz
Enlightened Equipment Revelation 40 (Stock)19.8 oz


The Therm-a-Rest Vesper 45 Quilt is a high-quality, ultralight, and ultracompact quilt that I found to be true to its temperature rating. It’s a great warmer-weather option for backpackers and fastpackers looking to minimize weight and bulk from their kit without minimizing features. There are ultralight quilts on the market which save weight with minimal features, but the Vesper manages to keep a 12-ounce weight while maintaining features found on much heavier quilts through the use of high-quality materials and smart design. If you’re looking to reduce the weight of your backpacking sleep insulation this year, the Therm-a-Rest Vesper 45 deserves serious consideration. 

Disclosure: Therm-a-rest donated a quilt for an honest review.

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About the author

Greg Pehrson is an ultralight backpacker who was bitten hard by the MYOG (make-your-own-gear) bug. He repairs, tinkers, and builds gear, often seeking to upcycle throwaway items or repurpose things from outside the backpacking world.


  1. Bill in Roswell GA

    Thank you so much for the review of Therm-a-Rest’s warm weather bag, the Vesper 45. Give Therm-a-Rest credit for willing to try new things. Some are hits, like the Neo Air series and some a “meh” like the wing valve. But when Therm-a-Rest decided to create a state-of-the-art sleeping bag they hit a homerun. You can tell they put a lot of time into the fit characteristics as well as the materials. When those two aspects are in harmony you have something special. I’m gushing on Therm-a-Rest bags as I have a Vesper 20. It’s outstanding in every way that I care about (I’m 5’7″, 210 lbs, wide shoulders, side sleeper on a 25″ wide pad). Per Greg’s review, the Vesper 45 also deserves to be held in high regard.

    The only mod I did to my Vesper was tie one side of the pad strap onto the quilt with dental floss (plain, not mint!) so that I wouldn’t lose it. It would be nice if Therm-a-Rest offered a down hood to use with the quilt, but there are plenty of those offered by cottage makers as well as Ali Express. And not to forget, when you buy Therm-a-Rest quilt or sleeping bag you get their Better Sleep Guarantee – you have 3 months to try it out and if you’re not satisfied you can return it for a full refund (purchase receipt needed). I’m not affiliated with Therm-a-Rest in any way, just an avid fan of certain gear.

  2. I have been using Vespers all Summer – one for me, and the other for my two Jack Russell terriers. It’s actually great for dogs – you can keep them warm, but easily move them in and out of the bag. I saved a few pounds, and considerable pack space, from not carrying two sleeping bags. No shivering either from any of us with our Vespers!

  3. Really like that ThermaRest have the under-pad connector strap attachments not at the edge but beside the lengthwise draft tubes to give them maximum efficiency. SMART!
    Then there is the neck snap which makes for a good baffle.

    No wonder this quilt is mummy bag warm.

  4. I bought the Therm-a-rest Vesper 45 for its features and I have not been disappointed. It’s incredibly light and small when packed down giving plenty of room to carry other essential items.

    Thoroughly recommended.

  5. Good review but should include some of the cons as well as pros. I bought the warmer version on steep discount which is fortunate as I’d return it if had paid full price. I have the vesper 20 F version regular size. All other features are the same as what was reviewed. I am 5’9″ and approximately 195 lbs, an older average American male who should lose 15-20 lbs.
    True great build quality and down . But the strap is flimsy and comes unhooked constantly at night. The snap is tiny and also unsnap easily. Definitely a good idea to permanently attach one end as suggested and definitely the lower strap connections are better. As for the snap I could tighten it by gently prying inward prongs on the female part of snap. Repeat gently! Easy to break. Definitely should have been a stronger snap.
    This quilt has cured me from ever buying another backpacking quilt as sleeping bags are so much better!! Why?
    When I rolled over at night I constantly was awakened by puffs of cold air even though I had a down parka, shirts, poly long underwear, and excellent Eddie Bauer Alpine Pro pants. I was at 37 degrees sleeping on snow with ground cloth, Regular Wide Thermarest Topo pad. As temperatures went down I had to retrieve my UL excellent PHD mummy bag to add to the mix as the poofs of cold air kept coming in. Also Do Not use a Wide pad with this quilt — the strap is too tight and got permanently damaged stretching in out around a wide (25″)
    I actually have problems with side puffs coming in even sleeping on a bed in a bedroom (chilled down to 55-60 F) while just in underwear– suggest use pajamas,.

    Am using this partly for visiting a friends so I don’t mess up her extra sheets etc but even then the narrow midsection is a problem.

    I do plan on using this still as the pluses (and incredible good deal I got) outweighed the negatives. Excellent down and water resistance, very warm on the top part, nice foot box — only one pair of socks needed (Darn Tough thicker ) even when in below freezing temperatures. Improvements are using a narrow mummy 3/4 insulated neoair, with fold up 3/4 closed cell pad under it. Use stretch straps with adjustment through all four loops on sides of pad to close up the “bare back” flaw in quilts in general. Why 3/4 length pads. I’ve found heat losses in the legs to be minimal to the ground as the weight is minimal compared to ones torso. The final assault to my sleep in my test run was a literal cold stab in the back. The wide pad gradually conducted the cold from the edges to make the whole pad cold even though rated 4-1/2 r value. I know the neoAir winter version would be better but it’s $250 abouts and would also waste space for the feet and legs where I’ve found through the years that a closed cell pad is sufficient or no pad at all.
    Suggestion use a mummy pad long or short with this thing .

  6. A) I think you lost one of the straps or it didn’t get included, i’m pretty sure the bags and quilts come with _two_ straps. I use both, and find that they really help keep things under control. Unlike David, my straps have NOT stretched after probably 20 uses, and i do love me a 25-in wide/3-in thick mat. I agree that they can pop up when moving the quilt/mat around, but i don’t recall that ever happening when i’m sleeping. (For reference, i’m 5’10, 200 lbs with a, er, roundish shape.)

    B) I’ve had a Vesper 20 for at least a couple years now, to complement a warmer-rated synthetic fill Thermarest quilt (don’t recall the name) with pretty much the same shape/features. The comments to this article illustrate how each of us sleeps differently! It’s alway interesting to witness the marked differences of opinion between proponents and opponents of quilts. Unlike David, if I do feel the occasional cold spot when tossing and turning at night, it’s never been enough to bother me and make me want to go back to a full-on sleeping bag. I typically use a liner for a few extra degrees of warmth, but mainly to keep the pad and quilt cleaner, and pretty much alway wear a thin Ibex long sleeve hooded top and long underwear — might help.
    Like the OP, i really like my quilt(s), find their temperature ratings believable — note that there’s a bit of a common slight of hand with the naming of the bags: “20F” or “45F” in the name corresponds to the “Extreme” temp rating, which is not where you’d typically want to use such a bag/quilt, at least not without complementing it with a very decent extra insulating layers. Second note, this is not an actual ISO/EN rating, as those are only for bags with a hood, I think. For quilts, it’s just a home-made “recommendation” — but thermarest seem pretty honest.
    The one flaw i wholeheartedly agree with, is the snap button to close up the top around your shoulders. a) it’s a bit of a struggle to snap shut when you’re an old guy with the flexibility of a 2×4, and b) it does snap off way too easily. I’ll have to see if i can clamp it a bit tighter as Dave described, but i’m pretty sure mine is plastic, so i don’t think that will work. It’s really only a bother when i’m snow camping in 10 or 20F outside temps (warmer in the hammock or tent, but still nippy ;-), otherwise it’s warm enough overall that i’m OK if i just vaguely tuck the very nice and fluffy collar around my neck.
    A couple extra bonus points:
    If you’re hammock camping, using a quilt makes wiggling into the sleep system easier than with a regular bag with zipper, and much easier than with a zipper-less bag.
    My 20F quilt packs maybe 1/2 the size of an equivalent down sleeping bag, one of the big plus of a quilt when bikepacking or winter camping.
    So, a very satisfied customer here, despite that one ^%$#@ flaw of the weakling snap.

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