Shown for illustration purposes only. People don't normally sleep outdoors during the day or with their glasses on.
If you're sleeping on the ground, a sleeping pad is a critical piece of an effective sleep system. Not only does it provide the obvious benefit of cushioning against the hard ground, but it also prevents you from losing heat to the ground during the night. As a result, you’ll want to have a pad included as part of your sleep system for ground sleeping. (Those using hammocks will likely prefer to use an underquilt).
Left To Right: Torso Length Gossamer Gear Uninsulated Inflatable Air Pad + CCF Heel Pad, Thermarest Self-Inflating Pad, Cheap Blue Closed Cell Foam Pad, Insulated Big Agnes Q-Core Air Pad.
Types of Pads
There are three types of pads typically used by hikers. They are closed cell foam (CCF), self-inflating, and air pads.
CCF
Closed cell foam is typically the least expensive and simplest option. A layer of foam creates a huge number of tiny air pockets, slowing the rate that heat is able to pass through. While the insulating ability can vary from one foam type to the next, thicker pads generally provide more insulation. CCF pads are durable but bulky compared to inflatable pads. Those using frameless packs may prefer having a smaller CCF pad to add some internal structure to a pack and for use as a sit-pad to rest on during the hike.
Self-Inflating
Many new campers start with a basic self-inflating pad such as the Thermarest pad shown above. It's super simple to use, though often after some experience, hikers will gravitate more towards the lower weight of a CCF pad or the lower bulk of an inflating pad.
Self-Inflating pads are made using two outer layers of fabric with open cell foam (similar to a sponge) in between. Unlike closed cell foam, open cell foam can easily take on air, or have that air pressed out of it. When the valve on a self-inflating pad is opened, air rushes into the foam causing it to expand and inflate the pad. Because it easily passes air through it, the foam used in these pads can’t offer the same level of insulating ability that a CCF pad can. They’re also limited in thickness, as using enough foam to provide more than about 1.5” of cushioning can be very bulky. While still packing smaller than a comparably-sized CCF pad, self-inflating pads still have more bulk (and weight) than air pads.
Air Pads
Above: An insulated air pad from Big Agnes. It's important to clear the ground of any sticks or rocks before using an air pad to prevent punctures even if you're in a tent or using a ground cloth. Be careful not to over-inflate your pad as well; over-inflation is less comfortable and more likely to damage the pad.
Air pads forego the foam used in either CCF or self-inflating pads. While they take quite a bit more time to inflate (as this must be done with either your breath or a pump), they’re able to pack much smaller than either of the other types of pads. They can range from completely uninsulated (to provide cushioning in warm conditions) to heavily insulated to reach very cold temperatures. The insulation used varies, with a synthetic insulation being most common, but down or even IR reflective material options are used as well. It’s important to avoid using your breath to directly inflate these pads in cold weather, as you’ll likely create condensation inside the pad, dramatically reducing its effectiveness no matter what insulation type is used.
The other drawback with an air pad is that the lightweight options use relatively fragile fabrics. Avoid sticks and rocks and avoid over-inflation (which can put too much pressure on the pad when you lay on it). These precautions are vital to ensuring a long life for your pad. Most pads include a patch kit to deal with any punctures, and we strongly recommend you carry that patch kit on your hikes, as an un-inflated air pad won’t offer any warmth.
R-Value
In your search for a good pad, you’ll frequently see references to R-Value. The R-Value is a measure of how much a pad resists warmth passing through it. A higher number means the pad offers more insulating value. As with quilts and sleeping bags, it’s critical to remember that a pad is just one piece of the puzzle. It does not create any warmth for you; if your body doesn’t have enough calories to burn, you’re still going to be cold.
Much of what confuses people about R-Values is that there isn’t a direct translation into a more recognizable temperature rating. In our own experience, it seems that most users are comfortable down to about 30°F with a pad that has an R-value of about 3. Typically, one wants an R-value of 5 or more for colder trips. The effect is additive, so adding a CCF with an R-Value of 2 to an air pad with an R-Value of 3 will provide a total of an R-Value of 5, which typically is the beginning of winter usability or shoulder seasons for those who sleep colder. Below is a simple guideline.
As with temperature ratings, keep in mind that these are only baseline numbers. Many factors can affect how much insulation you need. For example, leaves and pine needles are natural insulators; whereas rock will start out warmed from sunlight, and rapidly cool as it grows dark. If you purchased an expensive pad and are still getting cold, adding an inexpensive CCF can be a good way to stretch the temperature range to find out how much insulation you need for your trips.
The Q-core pad shown in this photo is an R5 pad, suitable for fairly cold temps, but the addition of the CCF pad extends the insulation even further besides helping to prevent punctures.
Pad Sizing
One area people often fail to realize potential weight savings is in sizing their pad. While width is fairly straightforward (if you’re off the edges of your pad, you should probably use a wider pad), length is a bit more flexible. In warmer weather especially, going with a torso-length pad can save a lot of weight, and placing your pack (or a sit pad) under your feet can supply all the insulation you need. Naturally it can be harder to manage this in colder weather, but with some creativity, you can reduce pad weight and bulk significantly by combining different pad types. CCF pads in particular are very easy to customize. If you bought a full-length and want it to be half-length, just cut some off. Too wide? Cut off some width. While some air pads can be modified to shorter lengths, doing so is more complicated, and more costly if it goes wrong.
On top is a full-length pad, and below that is an extremely minimal torso-length pad, with a CCF pad for your heels (a pad which can also be used to add some structure to a frameless pack). While a full-length pad is simplest, you can save a huge amount of weight, especially in warmer weather, by opting for a shorter pad length.
Comfort and Convenience
You’ve probably noticed I’ve said very little about comfort. Much like a good pair of shoes, something that fits you perfectly might not work so well for someone else. Some can’t stand CCF pads, finding them too bulky or too firm, while others don’t like the sensation of sleeping on an inflated pad, or they worry about puncturing it. In the end, this is where your experience using pads will inform your decisions. Don’t hesitate to experiment to find out what you like the best.