The Outdoor Research Helium is our Top Pick for the Best Lightweight rain pant. It is half the weight and packed volume of most of the options we tested and is one of the lightest and most compressible rain pants on the market. While it does give up a little in the way of "extra" features and durability, it still offers excellent storm protection. The Helium offers an excellent fit (though slightly smaller than average) with great freedom of movement and is durable enough for most backpacking trips, day hikes, or summertime mountaineering adventures (as long as there is minimal bushwhacking to be done). The Helium is also a perfect just-in-case layer for a wide range of activities and all of our testers simply loved how tiny it packed away.
Outdoor Research released an updated version of the Helium pant with new Pertex Diamond Fuse nylon fabric that is designed to be more abrasion-resistant. The updated model is exclusively available at REI now, and will be offered at other retailers starting in Autumn 2020. Take note that if you purchase this pant from anywhere but REI between now and then, you'll be purchasing the older model (which is the one we tested in this review).
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Our Analysis and Test Results
The Outdoor Research Helium is the lightest rain pant in our review and the best super-light rain pant on the market. More and more options are released each year, though the Helium remains at the top of our list. Most ultralight models offer very poor breathability, aren't very waterproof, and cross over the point of functionality because they are too fragile. This simply isn't the case with the Helium; it gives up a little bit in some of these categories to other much heavier models, but overall, it offers respectable durability, breathability, and storm worthiness - especially considering how crazy light and small they are.
We took the Helium pant out on a dozen or so trips using them for a little over 3-weeks. All of our testers were impressed with how tiny and light these pants were yet still provided pretty decent weather protection.
The Outdoor Research Helium uses Pertex Sheild+ fabric for its weather resistance. Pertex Sheild+ is a PU film coating laminated to a Nylon shell that coupled with the Helium's design, offers respectable weather resistance. Despite its impressively low weight, these pants performed above average in our hose and shower tests, as well as in real-world use.
When you first pick up this pair of rain pants, you immediately want to categorize it as a super lightweight pant that might not offer comfort or a functional design in exchange for saving weight. Our review team found that this was not the case. Our entire team loved how the low-profile elastic waistband felt, particularly when worn with a backpack. It proved to be one of the most comfortable contenders; the elastic waistband and shock cord was a breeze and kept our pants from slowing inching down. We found that these pants fit a wide range of users, but certainly run a little on the smaller/slimmer side of the spectrum. For folks that are forced to size up, there are three built-in elastic loops to accommodate suspenders.
Despite the slimmer than average fit, the Helium's range of motion was among the best in our review, featuring a solid design and excellent articulation. After extended use, our testing team found that these pants performed well for activities that demanded a fair amount of mobility, whether alpine rock climbing, Nordic skiing, trail running, or similar type activities.
Breathability & Ventilation
This contender does not offer any additional features to help with ventilation, though the Pertex Shield+ fabric proved to perform slightly above average in the breathability metric. In our side-by-side testing, we found these pants to be more breathable than some, like the The North Face Venture or Columbia Rebel Roamer. They were similar to the Marmot PreCip Pant, but not quite as breathable as the OR Foray.
We liked the internal fabric and texture. Several members of our testing team noted that it felt less clammy than other options, particularly the Marmot PreCip and The North Face Venture Half Zip.
The Helium doesn't provide much in the way of "extra" features; instead, its exceptionally low weight and compressibility are its main attributes. It does have a handful of additional features, making it easier to use and possibly allowing its wearer to save weight. It stuffs into its reversible back zippered pocket and is complete with a clip in loop, should you want to carry it on a climbing hardness or clip it to something else. Another nice feature is the loops, which can be found under the pant cuff; when attached with cord (and passed under the arch of the boot), they allow the pant cuffs to more or less function as gaiters.
We used this feature on two separate trips (one on snow) and felt this "built-in gaiter" created an exceptional seal around our boots, keeping snow and brush out. This feature gives the user the option to leave behind a separate dedicated pair of gaiters, further reducing their pack's overall weight.
The Helium pants are the most compact pant we tested - by a fairly sizeable margin. The design ensures the pant is lightweight and extremely packable. Even its closest competitors are about twice the packed volume, with several options being two-thirds larger. This light layer, which will practically disappear in your pack, will leave you more than prepared and willing to carry it in the event of an unexpected afternoon thundershower.
At 6.5 ounces, the Helium offer the lowest weight of any model in our review and is easily one of the lightest options currently on the market. It achieves its incredibly low weight from a range of design features (or lack of features).
A few of these features include sporting one single pocket. This contender is also made of the lightest external fabric in our review and has minimal-width seam tape, low gauge 1/4-length zippers, and a lower-profile elastic waistband. These pants might not be as durable and do not offer as many features as many other options, but as far as an excellent pant for backpacking and hiking, or as a just-in-case layer, the Helium is tough to beat.
This competitor features a 30D nylon shell, which is the thinnest in the review, though not by heaps. We found them plenty durable for most backpacking and hiking trips, but do think that if you end up doing much in the way of bushwhacking or off-trail travel, these lightweight pants might be destroyed quicker than other models. The Marmot Minimalist proved to be the most durable contenders in our review.
Ease of Use
The Helium pants are slightly below average in the ease of use category. The 1/4 length ankle zippers marginally assist in pulling the pants over low-profile tennis shoes; however, anything that is more substantial will prove to be nearly impossible, requiring you to remove your footwear. For folks with larger feet, it's likely that you'll always have to remove your shoes to don or remove these pants, as the pant legs are slimmer than average and the ankle length zippers do not provide much assistance. These pants feature one rear pocket and no hand warmer style pockets; overall, our testers did not find this to be a significant issue and most of our review team felt that carrying items in jacket pockets was generally more comfortable, regardless of the option.
A Note on Fit
These pants run small. We don't think you automatically need to buy the next size up, but if you tend to be in between sizes, we'd certainly recommend it.
The Helium pants are best for any application where pack space and weight are at a premium, whether that be backpacking, day hiking, mountaineering, or as a top layer for colder cross-country ski days. These pants are rad for what they offer, weighing in at 6.5 ounces. We love them for any backpacking or hiking trip when bad weather is in the forecast as long as the trip doesn't involve much bushwhacking, where the relatively low durability score might become a disadvantage. We'd use them while mountaineering or on snowshoeing trips, or for cold poor weather trail runs.
At $120, the Helium slightly tiptoes onto the more expensive side of rain pants, though are still affordable, especially if you're a weight weenie. For $20 more than many similarly designed pants, the Helium saves you 5-7 ounces, and is roughly half the packed volume of say, the 14 ounce Marmot PreCip Full Zip Pant, the 11 ounce Marmot Minimalist, or the 10 ounce Mountain Hardwear Stretch Ozonic.
For a combination of storm worthy functionality and minimal weight, the Helium is the best super-lightweight rain pant we've seen. If minimal packed size and weight are the most important factors driving your rain pant purchase, then this competitor is tough to beat. It isn't as durable or feature-rich as many other options, but it is extremely functional in design. It keeps you dry, is comfortable throughout, and offers excellent freedom of movement, blowing the competition away in the weight and packed size categories.
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