Shown for illustration purposes only. People don't normally sleep outdoors during the day, or with their glasses on.
You Need A Pad
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 hard ground (should you be camping in areas where site selection is limited), but many are surprised to learn how much heat is lost to the ground without a pad, even when using a full sleeping bag. As a result in almost any case 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, Cheapo Blue CCF Pad, Insulated Big Agnes Q-Core Air Pad.
Types of Pads
There are essentially three types of pads typically used for hikers. They are Closed Cell Foam (often abbreviated as “CCF”), Self-Inflating, and Air Pads.
The ubiquitous blue closed cell foam (CCF) pad. Can be purchased very inexpensively from big box stores, weighs very little, and is very simple to cut to smaller sizes for convenience. This is a very cost-effective way to add some warmth to an inflatable pad.
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 to the next, in general as you move towards a thicker pad the more insulation it can provide. They’re also relatively inexpensive and durable, but are 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.
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 CCF, 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 cushion can be very bulky. While still packing smaller than a comparably-sized CCF pad, Self-Inflators still have more bulk (and weight) than 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 groundcloth. Be careful not to over-inflate your pad as well; it will not only be more comfortable this way, but will be under less pressure and less likely to become damaged.
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 cushion 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 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 uninflated air pad won’t offer any warmth.
In your search for a good pad, you’ll frequently see references to R-Value. While the calculation of R-Value is very technical, for your purposes you just need to know that it’s 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 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. The pad is only one piece of the puzzle.
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 an R2 to an R3 Air Pad will provide a total of R5, 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 a base-line numbers. Many factors can affect how much insulation is needed, such as what material you're sleeping on (leaves and pine needles are natural insulators; 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.
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), but length is something most people don’t think too much about. In warmer weather especially, going with a torso-length pad can save a lot of weight, and by using your pack (or a sit pad) under your feet that’s typically all the insulation you need. Naturally it can be harder to manage this in colder weather, but with some creativity, one can reduce their pad weight and bulk significantly by combining different pad types. Also note that one of particular strengths of CCF pads is the ease with which they can be cut down to a size more in line with your needs. 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, a huge amount of weight can be saved, 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 not soft enough, 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.