The Best Bivy Sacks

Best Overall Bivy Sack

Outdoor Research Alpine Bivy

Weight: 28.5 ounces | Packed size: 4 x 15.5 inches

This offers the ideal combination of protection from the elements, comfort, and durability, not to mention strong rankings in other metrics. The Outdoor Research Alpine Bivy offers excellent protection from the weather so you can adventure with confidence.

While other models offer lighter weight and smaller packed size, the OR Alpine will never let you down when the weather turns for the worse. The OR Alpine was off the charts in its weather protection and even offers enough head space to get your critical equipment out of the elements as well.

Read Review: Outdoor Research Alpine Bivy

Top Pick for Ultralight Protection

SOL Escape Bivvy

Weight: 8.36 ounces | Packed size: 4" x 7.5 inches

The SOL Escape Bivvy comes out on top when you factor in the weight-to-protection ratio. At an almost unnoticeable 237 grams (or 8.36 ounces), you get wonderful warmth and protection from the wind and light rain.

If you need a bivy that can hold up to a big storm, the Sierra Designs or the Outdoor Research Alpine Bivy might be a better yet heavier solution. If your adventure requires you shave the weight and you have a reasonable expectation that the weather won't nuke, the SOL Escape is your bag.

Read Review: SOL Escape Bivvy

Best Buy

Sierra Designs Backcountry Bivy

Weight: 13.6 ounces | Packed size: 3 x 9.5 inches

The Sierra Designs Backcountry Bivy has a remarkable combination of weather protection, comfort, and weight savings. Judging by the competition making an "all-around" bivy is a difficult task, though Sierra Designs have done just that.

By adding a tab to elevate the ceiling with a piece of p-cord tied to a branch, the internal space and comfort are far beyond other bivies of similar size and weight. Having the bivy "pitched" also added to its water shedding ability. The features don't stop there!

Read Review: Sierra Designs Backcountry Bivy

Analysis and Test Results

Whether or not to bring a bivy depends on many factors, and everything from weight to weather to available space in an overnight pack can influence the decision. In our article How to Choose the Best Bivy Sack, we dive into the specifics between available styles and help to distinguish key features and best uses for each model.

Before purchasing a bivy sack, consider the conditions in which you will use it. The high mountains in winter? A boggy swamp in spring? Each of our reviewed products has unique characteristics that create compelling reasons to consider one for your next outing.

Value

We aim to not only bring you the best of the best but the highest value, especially when it comes to performance and cost. Our team of experts puts each model through a series of tests, awarding scores for a series of metrics. Determining which bivy will suit your needs will certainly have a list of pros and cons. What are you looking for? If the best value tops your charts, you'll want to explore our Price vs. Performance chart, which highlights the overall score and how that score relates to the price. Bivy sacks that land towards the bottom right show the highest "value."

Weather Resistance

A great shelter protects from whatever weather might arrive without negatively affecting the camping experience. Several factors come into play when considering which type of weather to prepare for. Is rain or snow likely? Will the nights be cold? The main element that affects weather resistance is the type of fabric used for the bivy. Is it a mesh that won't protect from any precip? Is it the ultimate in waterproofness that will keep you warm and dry in cold weather, but not breath well and leave you sweaty in warmer conditions?

Different types of fabrics work best in different situations. A wholly waterproof material, like Gore-Tex, will keep all the rain out, but even the most breathable versions have a harder time allowing water vapor from sweat or breath to escape. Ripstop nylon is lightweight and if treated with a durable water-repellent (DWR) coating is typically more breathable, but since it isn't entirely waterproof, is only ideal for lighter rain. The SOL Escape deviated from the norm by constructing a bivy from metalized spun-bonded olefin, which is typically used as a moisture barrier for home construction. This material provided excellent weather resistance while maintaining breathability.

Some bivies are made for four-season protection and can be used in wintry, alpine conditions. Other models strive to save weight and don't allow for a complete closure of the waterproof shell material, around the face, and so are best reserved for emergencies or milder rain and temps.

The most weather resistant models we tested are the four-season Outdoor Research Alpine Bivy and the BD Bipod, both of which are made entirely with waterproof materials and can be completely closed up in the nastiest winds and storms. The rest of the field offered decent weather protection, each bivy having its strong and weak points.

Like all camping shelters, the way it is used can affect weather resistance. When possible, picking higher ground or a clearing under a tree will add a bit of extra weather resistance from the natural environment, avoiding pooling water in a nasty deluge. Always check the trees overhead for dead limbs, or "widow-makers," which can break off dangerously (especially in a storm).

Weight

A good bivy should be a lighter camping option than a tent with the equivalent protection. A few of the lighter weight models have extra bug netting in key locations instead of shell fabric to shave some ounces — something a camper in a very wet and cold environment may not appreciate. Also, an additional tentpole like the ones included with the four-season models (OR Alpine and BD Bipod) might add a few ounces that just aren't needed if the top is to remain mostly open in dry conditions. Care should be taken to make sure your choice isn't too lightweight that it sacrifices the protection and comfort you desire.

The lightest reusable bivy is the SOL Escape. The heaviest is the Tennier, weighing over two pounds, which is still far lighter than a standard backpacking tent.

Packed Size

Many bivy sack users feel that small packed size is one of the key features they seek. Extra bulk in a pack often can't be afforded and, more than just the weight, the packaged size of the product can determine whether it is appropriate for the next trip or simply a large inconvenience that will get left at the car. The models that include separate tent poles can have the long obstructive sticks stored elsewhere (perhaps on the outside of a pack or along the inside wall) so that the bivy inside the stuff sack can be crammed into any available spot in a pack. By dropping down from a tent to a smaller bivy, you might be able to save up to five liters of space, allowing for a smaller pack overall or room for other essential gear.

We measured each product when packed up in its (usually provided) stuff sack. Some of the models had poles that could be added to the same stuff sack or stored in your pack separately. The SOL Escape offered the smallest packed size of all the products tested. The Tennier Woodland Camouflage was the largest.

Ventilation

Ventilation in bivies can be a tricky thing. Just like any piece of waterproof gear, the better a sack protects you from rain and weather, the less it breathes. How well a bivy ventilates and how much condensation builds up inside is a huge factor in its value and performance.

There are a lot of human factors that can make your night miserable even in an exceptional bivy. But of course, we at OutdoorGearlab are here to give you the info you need to make your experience in the wilds a great one. There are a few actions you can employ to make sure your bivy will perform to its highest abilities. The main issue is that your condensed breath or extra sweat from getting overheated can build up on the inside of the sack, causing a "rain" effect when moving or shifting inside. One of the easiest things to do to prevent condensation if you have dry weather is to keep the zippers open as much as possible. Even during downpours or extended periods of time where complete protection is necessary, we recommend "cracking" the mesh or zipper to allow some movement of condensed air inside.

If dry weather is not in the forecast, the two critical things to keep in mind are to make sure you are breathing outside the bivy and not to use a sleeping bag or pajamas (or whatever clothing you sleep in, if any) that are any warmer than what you need for the temps. If the temps are variable, or you toss and turn in your sleep (and can't easily ensure your mouth stays at the bivy opening), it might be a good idea to bring a synthetic sleeping bag instead of a down sleeping bag. Why? Synthetic insulation can still retain insulating properties and keep you warm if it gets damp or even soaked.

If your bivy can be staked out or has a pole to give you space around the head, taking advantage of these features will add extra air space between your body and the bivy walls, which significantly increases its ability to ventilate.

Comfort

Comfort is always an important criterion for outdoor gear, especially for gear that you rely on for shelter in backcountry situations. Time spent in an uncomfortable or cramped bivy with creepy-crawlies getting inside can turn a user away from bivies for good. The things we considered that contributed to the comfort rating of these each tested bivy included insect protection, roominess (volume and general size considerations), ease of use, and added features, such as gear pockets or straps that hold your sleeping pad in place.

Does your sack feel like a sarcophagus? While we might have enjoyed sleeping in cupboards or underneath the bed as children, most grown-ups prefer to have some space to toss and turn throughout the night. If you are choosing a bivy because you want a shelter for less weight and space taken up in your pack, you should also expect less space for you inside, but not to the point of discomfort. We compared not only floor space, but headspace and width at the shoulder, all of which influence the comfort rating.

Ultralight and minimalist models can often be less spacious to cut down on the amount of material used. Conversely, four-season models often have wire hoops or tent poles to help increase volume, leave room for the face and provide an experience very similar to sleeping under the stars with all the protection of a tent. The Sierra Designs Backcountry Bivy was an excellent combination of size and comfort features such as the ability to keep the ceiling away from your face with no added weight. The SOL Escape Was a bit on the snug side but was useable for our 5'11" gear tester.

Key Accessories

When planning what sleeping system works best for you, it's important to take all components into account. Your shelter, sleeping bag, and sleeping pad all work together to keep you warm and comfortable. We recommend pairing a bivy sack with one of the sleeping bags from our Ultralight Sleeping Bag Review. Our favorites were the Katabatic Gear Palisade and ZPacks Classic for their comfort and lightweight. As far as sleeping pads, some of our favorites include the Therm-a-Rest NeoAir XTherm and the Therm-a-Rest NeoAir XLite. Through our testing, we have found these two to be amazingly comfortable and warm even with their low weight. For a more detailed look at all the sleeping pads, we reviewed, check out The Best Sleeping Pad Review.

Conclusion

Climbers and ultralight backpackers alike may be interested in a bivy for numerous reasons. In addition to an emergency shelter, these products can be a lower weight and a smaller alternative to a tent. A bivy can allow you to sleep in a multitude of places where a tent would not be possible. A lot of factors need to be considered when selecting a bivy, ranging from weather resistance to pack size. For more information on whether a bivy is the right choice for you and what to consider when making your purchase, check out our Buying Advice article.

When to Switch from a Tent to a Bivy?

The most common reasons to buy a bivy sack rather than a tent are to reduce pack weight and pack size by utilizing a sleeping system that is both lighter and smaller, yet still able to provide some shelter from the elements. But there is an active debate in the ultralight backpacking community about whether bivy is a better solution than an ultralight tent or a UL tarp shelter. Bivies are still easier to set up than even the best UL tents and tarps, especially if you are looking for a solo shelter equipped to deal with the stormiest weather, and mainly winter snow conditions.

We explore this question in more detail in our buying advice article, and recommend that article for those interested in considering ultralight tents or tarp shelters as an alternative to bivies, or to augment them (many people use UL tarps and bivies together to create a uniquely lightweight solution with excellent weather protection). But, we'll try to summarize the most salient points below.

A tent offers comfort with a lot of floor space which gives you room to sit up, read and hang out, or store gear. An ultralight tarp can also offer a similar amount of room that a tent does, with even lighter weight, and improved protection in the rain over bivies. In a sustained rainstorm, a tent or tarp is much more comfortable than bivies. Many people don't realize that some bivies do give you enough headspace to read or to sit up a bit so you can comfortably sip your coffee or slurp your miso soup.

Regardless of whether a bivy has those features, some of these traits are not needed by everyone, and they are worth sacrificing in the name of less weight and space used up in your pack. By shedding extra material, poles, zippers, and doors — bulky components of a tent that are difficult to avoid — a camper can be reasonably comfortable while sitting out poor weather in the smaller enclosed space of a bivy. However, there is a limit to how many hours or days a person can comfortably wait inside a cramped bivy.

For this reason, we recommend that extended backcountry trips with the possibility of poor weather might be better spent in a larger tent or tarp. For quick trips where a storm can creep up in a moment's notice, or for adventure excursions that require the lightest packs so you can be fast on your feet, a bivy sack can perform and protect as well as a tent.

Indeed, at first glance, a bivy is just a micro-tent, lighter and smaller with all the protection and less bulk. They are also much more mobile, able to be used on any flat surface long enough to stretch out on, and narrow enough to fit on tight rock ledges and small patches of soft grass. And some bivies don't need trees or anything to anchor them down or guy them out. They can also keep you warmer in cold weather than some tents do, and certainly warmer than a quick tarp setup.

The bottom line is that you can make a bivy work where a tent will not — high rock ledges, tight snow caves, tiny flat campsites on rocky terrain. Depending on your needs, a bivy can run anywhere from $20 to $300 and fluctuate from a fraction of a pound to up to two pounds. While you can now find options for full-sized ultralight tents that are less than two pounds, these tents aren't usually four-season shelters, and they lack the versatility that a bivy sack of similar weight will give you. Another reason people will use a bivy is when they are headed on long adventures and want something to protect them from the elements in an emergency or if they find themselves unexpectedly benighted. Bivies give you the most versatile and lightweight option, and for those who prefer sleeping under the stars, a great alternative to tent camping!