Outdoor Research Helium UL Rain Pants Review
Ultralight, breathable, and flexible rain pants for cool-to-warmer weather high-output pursuits
May 23rd, 2026
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Our verdict
The Outdoor Research Helium UL Rain Pants are breathable, packable, and stretchy wet-weather protection for warmer conditions, best suited for ultralight hikers, backpackers, and travelers. They’re some of the lightest rain pants on the market–they easily pack down into their chest pocket, take up almost no space in a pack, and are both extremely breathable and flexible.
Because these rain pants are so lightweight, we named them Best Ultralight Rain Pants in our Best Rain Pants guide.
That said, due to the nature of their breathable, ultralight construction, these pants are not durable. In rain gear, a lower-weight fabric that lends itself well to breathability and packability will also have decreased resistance to tears and abrasions. During testing, they tore twice in as many days. Neither tear was large, but both were irksome and the sign of tearing doesn’t bode well for our upcoming season on the Appalachian Trail in Maine. And for rain pants that cost $170 and are marketed as durable, the ease with which they tear is a bummer.
The Helium line runs somewhat slim and is remarkably comfortable for extended use while backpacking in warm-ish and profoundly rainy conditions—nearly every day on the well-maintained West Highland Way in early April, for example. These rain pants are a great pick for ultralight and super-breathable, easily-packable rain pants—if they aren’t likely to see many abrasive or bramble-ridden trail conditions. For less maintained trails, bushwhacking, or situations where the expected temperature will dip below around 55ºF (13ºC), a more rugged pair of rain pants such as the Outdoor Research Foray rain pants would be a better pick.
However, if you’re looking for a truly ultralight pair of rain pants that sacrifice some features such as extra pockets or more rugged waterproofing in favor of next-to-weightlessness and easy packability, look no further– the Helium UL rain pants were made for you.
Outdoor Research Helium UL rain pants
men's
Women's
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Outdoor Research Helium UL rain pants specifications
Price: $170
Weight: men’s medium 6.2 oz, women’s medium 5.8 oz
Fabric: Toray Dermizax 2.75-layer laminate
Waterproof rating: 20,000mm
Breathability rating: 20,000g/m2/24 hrs
Face fabric denier: 15 denier
DWR treatment: PFAS-free polyurethane film
Fit type: Regular, but runs a bit slim (I sized up one size)
Adjustments: Drawcord elastic waistband, elastic cuffs with gripper tape
Leg zips: Ankle zippers with snap closure at cuff
Pockets: One zippered back pocket with mesh interior
Ventilation features: n/a
Packability: Packs into back pocket, interior loop connection point
Sizes and inseam options: S-XXXL, 29.5in and 31.5in inseams
Gender-specific versions: Yes
Comparison table
| RAIN PANTS | MSRP* | WEIGHT | WATERPROOFING | PFC / PFAS- FREE | SIZES |
|---|---|---|---|---|---|
| Outdoor Research Helium UL Men's Women's |
$170 | 6.2 oz (men's), 5.8 oz (women's) | Toray Dermizax 2.75-layer laminate | Yes | S - XXXL (men's, short and regular), XS Short - XXL (women's, short and regular) |
| Outdoor Research Helium Men's Women's |
$130 | 11.3 oz (men's), 10.23 oz (women's) | bluesign-approved Pertex Shield Diamond Fuse 2.5L | No | XS - XXXL short, regular, tall (men's), XXS - XXL regular, short (women's) |
| Marmot PreCip Eco Pants Men's Women's |
$100 | 8 oz (men's), 7 oz (women's) | NanoPro | Yes | S - XXL (men's), XS - XL (women's) |
| Outdoor Research Foray/Aspire 3L Pants Men's Women's |
$199 | 13.6 oz (men's), 13.2 (women's) | bluesign-approved AscentShell Dry 3L; Direct.Dry DWR | Yes | S - XXXL (men's), XXS Short - 4X (women's) |
Best for
Anyone looking for ultralight, stretchy, and breathable wet-weather protection while peakbagging, hiking, backpacking, commuting, or traveling in warmer conditions.
Hikers who are gentler on their gear or who don’t hike in brambly, rocky areas
Ultralighters looking to round out their kit with full-leg-coverage rain protection (i.e., wearing more than just a rain kilt)
Wet-weather trail running, bikepacking, or other high-output activities in warmer environments where a full range of motion is needed
What we liked
Stunningly lightweight— the lightest rain pants I’ve tested
Packed volume is small and they compress further in the pack, making them ideal for ultralight traveling or trekking
Breathable enough to be more than tolerable in warm conditions for people who tend to run hot
Flexibility of fabric is exceptional: see photo of me doing a split in these with no visible wear to the middle seam or its tape afterwards
What could be better
Tear on the right leg of the Outdoor Research Helium UL rain pants.
Not durable–tore twice during normal wear, once while putting the pants on hastily in a storm and another time on a non-thorny bush
Wets out between two and three hours into wind-driven rain which is not ideal for consistent rainy conditions, especially when pushing the boundaries of how cold these pants remain suitable in
How we tested
The Helium UL rain pants were also appreciated in Uruguay when stormy weather rolled in.
We tested the Outdoor Research Helium UL rain pants on power walks around Manhattan in springtime, Uruguay in autumn, and backpacking the West Highland Way in Scotland in early April. They were most pleasant as rain pants in New York and Uruguay for conditions-related reasons. New York spring was more or less warm, above 60ºF, as was Uruguayan autumn, but the West Highland Way brought wind and drenching rain in temperatures from the low 40s to the low 60s (ºF). On the latter end of that, these pants were a lovely shield from the mild to moderate wind and rain.
They’ve been a great addition to my day pack, which is an absurdly large fanny pack, in both Uruguay and Manhattan—sometimes I don’t feel like checking the weather and these are the perfect size and weight to just keep on hand.
Their most rigorous testing occurred over the length of the West Highland Way, where early spring weather is known to be volatile and rainy. My friend says it’s so the wildflowers later on can be as beautiful as they allegedly are. Much of the trail through the highlands is exposed fields of sheep and plains, absent of trees to break the wind. Much more of the trip was spent relying on these rain pants than anticipated, and on all but one and a half of the days these pants served me well enough. Intermittent rain usually means taking rain gear on and off over and over again, which is irksome, but the Helium UL pants are breathable enough to be kept on comfortably all day while hiking or even during breaks in the rain.
We also tested these pants alongside others in our Best Rain Pants guide, like the Outdoor Research Foray rain pants, to directly compare waterproofing, breathability, comfort, fit, durability, weight, packability, and more.
Performance in the field
The Outdoor Research Helium UL rain pants in use on the West Highland Way in Scotland.
Waterproofing
The Toray Dermizax 3D 2.75L laminate of the Helium UL rain jacket and pants differs from 2.5L or 3L laminates in a few ways. One is in what those laminated layers are. A 3L laminate consists of bonded inner liner fabric, waterproof membrane, and face fabric layers where a 2.5L laminate loses the inner liner fabric in favor of a coating on the interior, which saves weight and increases packability. But the Helium UL’s 2.75L laminate is neither– it’s got a subtly textured, microscopic raised-dot pattern printed directly onto the waterproof membrane which helps increase airflow with greater durability in the innermost layer.
And the other big way the Toray Dermizax 3D 2.75L differs from most other rain gear on the market is that instead of using a microporous membrane that allows vapor to escape while keeping water out, it uses a hydrophilic membrane without pores which absorbs sweat and moves it outward so that during high-output activities there’s less of that abhorrent clammy-rain-gear feeling.
Though these pants are some of the most comfortable rain pants I’ve tested during high-output activities in cool-to-warm weather, their lightweight fabric wets out in constant, wind-driven downpour after a little more than three hours. For many adventures, this is a fine duration of time to remain dry; for others, when the rain is constant and cold, it is not.
Breathability and ventilation
The Helium UL rain pants could become favorite warmer-weather rain pants in large part due to their outstanding breathability. Though their side zippers are confined to the ankle area alone with elastic ankle cuffs that don’t adjust, the fabric itself does well at allowing sweat and human vapor to evaporate quickly.
They’re relatively windproof too, though they’re noticeably more breathable than other rain pants I’ve tested, they successfully block the wind in most conditions. Keep the duration and intensity of the stormy weather you expect in mind when choosing between these pants and more robust ones, though.
On an especially miserable and memorable day with temperatures hovering around 40ºF (4ºC), the Helium UL pants were simply not the right pick. The breathability that made them so nice on warmer days felt malevolent as the wind seemed to blast clear through them. After a little over three hours of consistent wind-driven rain and sleet, the torrent of external moisture made its way through the membrane—unfortunately, there were more cold hours to go. Not the pants’ fault, but a genuine reminder to keep in mind the conditions they’ll be worn in– these were just not the right choice for a day with that kind of forecast.
Comfort and fit
The Outdoor Research Helium UL rain pants are overall very comfortable, in large part due to the total range of motion they offer their wearer, with stretchier fabric than most other rain gear on the market. They’ve got a good next-to-skin feel that doesn't get too clammy during high-output activities which is a must while wearing in warmer weather—which is when I’m personally most likely to pick them over other rain pants.
I sized up to avoid the notorious overly slim fit of the former Helium line and found that these pants don't run as slim as their previous edition. This time, I’ve got more than enough room for easy layering if needed—my personal preference is for rain gear to be on the baggier side though I’d likely have been fine in the smaller size too. If you like to have sufficient room for layering and/or you’ve got surprisingly large thighs like I do, I’d recommend sizing up.
The Helium UL rain pants have a medium-high rise which helps to keep rainwater from running down into the wearer’s pants—a must in drenching conditions. The waistband adjusts easily with a drawcord but it’s somewhat comfortable; the grippy elastic that helps keep the pants from riding up or falling down while in motion is not especially pleasant against the skin.
Durability
Worn away fabric on the left leg of the Outdoor Research Helium UL rain pants.
Put simply, these pants are just not that durable when it comes to abrasion resistance and tear strength. I’ve been gentler on them than I am with most rain pants I wear since I haven’t tested them in Maine yet, but have already managed to tear them twice.
Once on the West Highland Way when I brushed lightly against a bush akin to a bundle of tall, barely-spiky grass, the other time in Uruguay against the sole of my shoe as I was putting them on in a sudden rainstorm. Both times I was surprised at how easily the fabric succumbed to relatively non-hostile conditions.
With extended use of several pairs of rain pants from a spread of brands over the last couple years, the only ones that have torn with comparable ease were the loathsome Frogg Toggs. If you’re hiking somewhere rocky or brambly—such as the Bigelow Mountains in Maine where I’ll continue testing these pants over the summer and fall—there’s a high likelihood of at least your cuffs getting shredded on foliage or granite as you walk.
Weight and packability
The Outdoor Research Helium UL rain pants are extremely lightweight and easy to pack. Weighing only 6.2 ounces for the men’s and 5.8 for the women’s, they’re not only ounces lighter than similarly advertised rain pants on the market but pack down into a smaller, more compressible size. The back pocket doubles as a stuff sack with an attachment loop, and the stretchy mesh makes shoving the pants into this pocket a breeze. For an ultralight kit that’s missing the coverage of rain pants on days when it’s not warm enough for a rain kilt, these are the pants to have.
Ease of use
Aside from tearing a bit while putting them on that one time, these were relatively easy to put on over both trail runners and boots with the snap opened and the ankle zipper fully unzipped. The cuffs are functional: though not adjustable, the cuff elastic keeps most splashing mud and debris out. The drawcord waistband is easy to adjust with a pack on.
The mesh back pocket is spacious enough for an iPhone or a standard-sized can of soda, but isn’t accessible with a pack on. Packing the pants into that pocket is quick and straightforward—just shove, zip, and clip.
Features
Toray Dermizax 2.75-layer waterproof fabric
The Toray Dermizax 2.75L fabric is a stretchy, lightweight, water and wind resistant polyurethane-based laminate that provides the lightweight, barely-there feeling sought in ultralight gear with water and wind resistance solid enough for use on all but the most miserable of rainy days. It is inherently PFC/PFAS-free.
Back pocket stuff sack
The Helium UL pants pack easily down into their back pocket, which doubles as a stuff sack and features an attachment loop. The pants also compress at the bottom of a pack when not in use and packed into their pocket.
Ankle zippers
On a windy, downpour-ridden day on the West Highland Way, rain blew through the ankle zipper and splashed up through the cuffs.
For ease of putting on and taking off the Helium UL rain pants with shoes or boots on, there is a water-resistant ankle zipper with a snap closure at the cuff. They also feature a lace loop to keep the pants secure at your shoe. After a couple of hours in consistent moderate rain, a decent amount of water enters through the zipper.
Elastic cuffs with gripper tape and lace loops
Though the ankle cuffs are not adjustable, they are elastic and feature gripper tape that keeps them on securely while helping to seal out splashage– and this method of sealing functions as well as adjustable cuffs would, without the weight of the drawcord and plastic adjustment piece.
Gusseted crotch
In addition to having fabric with a relatively high degree of elasticity for increased mobility, the Helium UL pants have a gusseted crotch– an additional piece of fabric on the center seam which allows a greater range of motion with decreased risk of tearing during use.
Elastic waistband
The elastic waistband of the Helium UL rain pants has an adjustable drawstring and stays in place well while in use during all-day storms.
Reflective elements
The Helium UL pants have a reflective logo on the thigh for increased visibility in conditions with low light, which is especially useful for night hiking in the rain.
Gender-specific fit options
The Helium UL rain pants come in gender-specific fits. The men’s version comes in two inseam lengths– short, 29.5 inches and regular, 31.5 inches, where the women’s version has 28 inch and 30 inch inseam options.
Infinite Guarantee
The Outdoor Research Infinite Guarantee® warranty covers gear failure due to defects in the first 60 days after purchase and not due to damage that occurs during use or wear and tear over time. You can increase the longevity of your gear by washing and drying it regularly, reapplying a DWR when necessary, and being careful not to cause undue abrasions on rocks, wood, or sharp foliage.
Sustainability
The polyurethane Dermizax fabric by Toray is PFAS-free by nature, and the DWR treatment applied is in accordance with Outdoor Research’s commitment to no intentionally added PFAS and PFCs in their products since early 2025.
Outdoor Research Helium UL rain pants vs. similar rain pants
The Outdoor Research Helium UL rain pants are lighter, stretchier, and more breathable than any other pair of rain pants I’ve tested, and more expensive as well. They’re also less water and windproof than the others.
At a slightly higher weight and with a lower price are the Marmot PreCip Eco rain pants and the REI Co-op Trailmade rain pants. The PreCip Eco rain pants are $120 and 8 oz per pair, and the Trailmade rain pants are $70 and 7.8 oz per pair. The Marmot PreCip Ecos have held up the best over extended testing of the three and are almost as comfortable as the Helium UL rain pants, though with less elastic fabric and a lower degree of breathability during high-output pursuits. The Helium UL rain pants have outperformed any other pair of rain pants I’ve tested in the breathability department, in fact.
Should you buy the Outdoor Research Helium UL rain pants?
Kicking off the West Highland Way with a rainy terminus photo.
Buy if…
You have a sizable rain pants budget and are an ultralighter looking for some of the stretchiest and most breathable rain pants out there for warm-weather, high-output, storm-accompanied activities.
Skip if…
You already own lightweight rain pants or are looking for a pair of robust, long-lasting, 3-season rain pants with more ventilation options. For use on non-smooth, less-maintained trails, the tear strength and abrasion resistance sacrificed in the name of weightlessness and increased breathability will likely result in pants that don't stand the test of time.
Where to buy the Outdoor Research Helium UL Rain Pants
The Outdoor Research Helium UL Rain Pants are popular, so you have options when it comes to retailers. Here are some of the pros of the retailers.
REI
Pros: 100% satisfaction policy for 1 year; 10% dividend for members.
Amazon
Pros: Free 2-day shipping with Amazon Prime membership
Backcountry
Pros: Frequent sales for Expedition Perks members (free to join), fast shipping, Gearhead chat customer service is excellent
Outdoor Research
You can sometimes find more options when purchasing directly from the retailer. Sometimes, purchasing directly from the retailer can make it easier if you need to make a warranty return, such as if there is a defect.
Advice on where to buy
In general for apparel, we recommend purchasing from a place with easy or free returns, like REI. Trying on shoes is an important way to get the sizing right. With both those retailers, if your funds allow, you can buy two sizes and easily return one. Additionally, check reviews to see whether other users recommend sizing up or down.
Similar rain pants
Marmot PreCip Eco rain pants
MSRP: $100
Sizes: S - XXL (men's), XS - XL (women's)
Weight: 8 oz (men's), 7 oz (women's)
Waterproof fabric: NanoPro
PFAS free waterproofing: Yes, PFC-free recycled nylon
Face fabric: 100% Pre-Consumer Recycled Nylon, Ripstop
The Marmot PreCip Eco rain pants are only a couple ounces heavier than the Helium UL pants and they’re made from 100% recycled nylon. While not quite as breathable, they’re burlier and more affordable while still remaining ultralight, and are our best affordable rain pants pick.
The PreCip Ecos pack down into their pocket to a comparable size for easy storage just like the Helium UL pants. For 3-season travel, backpacking, or hiking they're a sturdier pick with a very small weight penalty. Over the nearly two years I’ve regularly worn these backpacking and hiking in the Northeast, they've yet to have any major tears and have remained consistently water and wind-resistant with minimal upkeep.
Marmot PreCip Eco rain pants
men's
Women's
Outdoor Research Foray (men’s) and Aspire (women’s)
MSRP: $199
Sizes: XS - XXXL (men's)
Weight: 13.6 oz (men's)
Waterproof fabric: AscentShell Dry 3L
PFAS free waterproofing: Yes, PFC-free recycled nylon
Face fabric: AscentShell Dry 3L, 40-denier recycled nylon
The Outdoor Research Foray/Aspire 3L rain pants are the Helium UL’s more robust, environmentally friendly cousin. They feature a 100% recycled nylon 40-denier 3L laminate and a higher weight (13.6ounces, so more than double that of the Helium UL) and a similar price point, the Foray pants are significantly more durable and resistant to wind and rain than the Helium UL pants. With a looser fit and a ventilation zipper that goes from the ankle to the mid-thigh, the Foray pants are a better choice for long-term three-season wear hiking, backpacking, or doing wet-weather trail work.
Outdoor Research Foray and Aspire
men's
Women's
Why you should trust us / About the author
Testing the flexibility limits of the Helium UL rain pants’ fabric, hypermobility-style.
Elliot Koeppel is from New York and graduated from Tufts University with a B.A. in History in 2023. He began his six-month thru-hike (and first-ever backpacking trip) of the Appalachian Trail the next week. Since then, he’s hiked the Colorado Trail and West Highland Way, and worked near the A.T. in Virginia for the start of the 2025 thru-hiking season. Over the winter he worked in a backcountry ski and snowshoe hut in Maine, and this spring through fall he’s returning to his role as the ridgerunner on the Bigelow Mountain section of the A.T. in Maine for a second year.
Due to environmental circumstances like working as a summit steward, varying luck with forecast accuracy, and occasional moments of hubris, Koeppel has spent a great amount of time in foul weather in places including Uruguay, Colorado, Maine, and Scotland.
Koeppel has been testing a range of thru-hiking apparel and rain gear for Treeline Review since 2023. In his free time, you can find him hiking, looking for rocks, making jewelry, or listening to Van Halen—David Lee Roth era.
