R-value measures thermal resistance — how well a sleeping pad insulates you from the cold ground. Higher R-value means better insulation. R-values are tested to the ASTM F3340-18 standard, making them comparable across brands. R1 is minimal insulation; R6+ is suitable for extreme cold.

Can I stack sleeping pads?

Yes, R-values are additive. Placing an R2 foam pad under an R3 inflatable pad gives a combined R5 — suitable for winter camping. This is a popular lightweight strategy: a cheap CCF (closed-cell foam) pad adds significant insulation under your main pad.

What R-value do I need for UK camping?

For summer (June-August) camping in the UK, R2 is sufficient. Spring/autumn requires R3-4. Winter hill camping in Scotland needs R5+. If you sleep cold, add 1-1.5 to these recommendations. The ground in the UK stays cold even in summer, especially on mountain pitches.

What R-value do I need for snow camping?

Snow camping typically requires R5 or above. Snow insulates from wind but conducts cold. At -10°C or below, aim for R6+. Always combine an inflatable pad with a foam pad for redundancy — if the inflatable deflates, you still have some insulation.

CampCalcs

Ground Pad R-Value Calculator

Calculate combined R-value when stacking sleeping pads for cold weather camping.

Pad 1 R-Value

Main sleeping pad

Pad 2 R-Value

Secondary pad (optional)

Pad 3 R-Value

Third pad (optional)

Expected Temperature

Temperature for this process

Sleeper Type

Enter the sleeper type

How We Calculate This

Combined R-Value

Combined R = Pad 1 R-value + Pad 2 R-value + Pad 3 R-value

Recommended R-Values by Temperature

10°C+: R1, 5-10°C: R2, 0-5°C: R3, -5-0°C: R4, -10°C: R5.5, -20°C: R7

Cold sleepers should add 1-1.5 to the recommended value.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify conditions and use proper safety equipment outdoors.