Which sleeping mat do I need?

Most people who are cold in a tent blame the sleeping bag, and most of them are losing heat downwards into the ground. A sleeping bag insulates by trapping air in loft, and the loft under you is crushed flat by your own weight, so it does almost nothing. The mat is what stops the ground taking your heat, and it is routinely the cheapest sleeping upgrade available.

Step by step

1. Learn what R-value means.R-value is a standardised measure of thermal resistance — higher means more insulation from the ground. Since 2020 a common testing standard means figures from different brands are genuinely comparable, which they were not before.
2. Match the R-value to when you camp.As a working guide: up to about 2 for warm summer nights, 3 to 4 for general three-season UK camping including cold spring and autumn ground, 5 and above for winter, frost and snow. Cold sleepers and anyone camping on stone or in a vehicle should go up a step.
3. Remember that R-values add.A closed-cell foam mat under an inflatable mat gives you the sum of the two, protects the inflatable from sharp ground and gives you a backup if it punctures. This is how most people manage winter camping without buying a specialist mat.
4. Choose the type deliberately.Closed-cell foam: cheap, unpuncturable, insulating, bulky, and firm to lie on. Self-inflating: open-cell foam plus air, comfortable, moderately compact, moderate weight, and repairable. Air mat: thickest, warmest for the weight, packs smallest, most expensive, and a puncture ends its usefulness until repaired.
5. Get the length and width right.A mat shorter than you means feet or shoulders on cold ground; short mats are a deliberate weight-saving choice with a rucksack under the feet. Standard width is about 51cm, which is narrow for many people — wide versions exist and are worth it if you sleep on your side or move about.
6. Consider thickness for comfort, separately from warmth.Side sleepers need enough depth that the hip does not bottom out — usually five centimetres or more on an air mat. Warmth and comfort are related but not the same thing, and a thin mat with reflective layers can be warm and still uncomfortable.
7. Check the noise and the surface.Some lightweight air mats crackle audibly with every movement, which matters in a shared tent. Textured or brushed surfaces stop the sleeping bag sliding off in the night.
8. Weigh the packed size against how you carry it.For backpacking, packed size is often the binding constraint rather than weight. For car camping, buy the thickest and most comfortable thing you can, or a proper camp bed.
9. Take a repair kit.Every inflatable mat should travel with its patches. A puncture in an air mat on a cold night without a patch means the ground takes your heat all night.
10. Inflate it by pump, not by mouth, if you can.Breath carries moisture into the mat, which over time supports mould inside and can degrade insulation in mats with down or synthetic fill. Most modern mats come with a pump sack.

Tips

• Storing an inflatable or self-inflating mat unrolled with the valve open is what keeps it working. Compressed storage kills the foam.
• In cold conditions, a cheap foam mat under everything also stops sharp frozen ground puncturing an air mat.
• For car camping, an airbed is comfortable and thermally poor — the large air space circulates and carries heat away. Put a blanket or foam mat on top of it.
• A mat is worth more than an expensive bag if you have to choose. Fix the ground first.
• Check the R-value figure is quoted to the current standard. Old marketing figures and vague words like 'four season' are not comparable.

Common mistakes

• Buying a warmer sleeping bag to fix being cold at night — The insulation underneath you is crushed flat and contributes almost nothing. Ground conduction is the loss, and only the mat addresses it.
• Blowing an air mat up by mouth every trip — Moisture accumulates inside, encourages mould and, in mats with insulating fill, degrades the fill. Use the pump sack.
• Leaving a self-inflating mat rolled tight in a stuff sack all year — The foam takes a set and stops recovering, and the mat progressively loses both loft and R-value.

If it doesn't work

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