Sleeping Pads Explained: R-Value, Thickness and Types

Your sleeping pad matters as much as your bag, because the ground steals your warmth. R-value scores that warmth. Pick a number for your coldest expected night, add thickness for comfort, and choose a type that fits how you travel. Here is what the jargon actually means.

Why the ground, not the air, makes you cold

This is the single most important idea. Lie down, and your body weight crushes the insulation in your bag flat beneath you, so it stops working there. Cold then flows straight out of you into the ground, which acts like a giant heat sink. That is why a warm bag still lets you freeze from below. Your sleeping pad puts a layer of insulation between you and the ground, doing half the work of keeping you warm.

R-value: the warmth number

The key warmth spec is R-value, which measures how well a pad resists heat flowing through it. Higher means warmer. As a rough guide, an R-value around 2 or below suits warm summer nights. Around 3 to 4 covers most three-season camping, spring through autumn. 5 or more handles cold weather, winter and snow. R-values also add up, so stacking two pads combines their numbers, handy for winter. If a pad states no R-value and mentions only a thermal or reflective barrier, treat it as a helpful three-season pad, not a guaranteed cold-weather one.

Thickness and comfort

R-value is warmth. Thickness is mostly comfort. A thicker pad keeps your hips and shoulders off hard ground, which matters enormously for side sleepers. Thin foam pads of an inch or so are tough and firm. Thick inflatable pads of three to four inches feel far more like a bed. A well-cushioned inflatable pad like the CKG 4-inch sleeping pad shows that off-the-ground comfort while still packing down small.

The three types of pad

Three main styles exist, each a trade-off. Closed-cell foam pads are tough, indestructible and never puncture, but bulky and firm. Self-inflating pads hold foam inside that draws in air when you open the valve, balancing comfort, warmth and reliability, though they weigh more. Air pads, the inflatable kind, are the most comfortable and packable, and modern ones can run very warm, but they need inflating and can puncture. Many backpackers carry an air pad for comfort and weight. Car campers often prefer a thick self-inflating one.

Weight and pack size

Carry your gear, and weight and packed size matter a lot. Car camp, and they barely register, so you can prioritise thickness and comfort. Air and self-inflating pads pack far smaller than foam. Be honest about your trips. An ultralight pad is wasted on someone who drives to the campsite. A huge comfy pad is a burden to a backpacker.

Living with an inflatable pad

Choose an air pad, and a few habits keep it working. Clear sharp stones and thorns from your tent floor before laying it down. Carry the repair patch that usually comes with it. Inflate it not-quite-firm so it cushions rather than bounces. Blow it up with the stuff sack or a small pump rather than your breath where you can, since moist breath inside a pad can, over time, encourage mould. Store it unrolled at home with the valve open, so the foam or fabric lasts.

The bottom line

Match the pad to your trips. Pick an R-value that suits your coldest expected night. Choose enough thickness for comfortable sleep, especially if you are a side sleeper. Settle on a type and weight that fit whether you backpack or car camp. Get the pad right and you sleep warm and rested, which does more for a trip than almost any other piece of kit.