A backpacking or camping sleeping pad’s R-value measures its resistance to heat loss to the ground when you lie on it at night. Pads with higher R-values do this more effectively than pads with lower R-values. R-value isn’t a measure of warmth per se, but of a pad’s ability to prevent the loss of the warmth that your body generates. It’s just like the R-value used to rate home insulation.
Sleeping Pad R-Values and Air Temperature in Degrees
What’s the correlation between air temperature and sleeping pad R-values? When do you need a pad with a higher R-value? This table is based on Exped’s recommendations in Fahrenheit and Celsius degrees.
|Air Temperature (F):||50||43||36||29||22||15||8||0||-7||-14||-21||-30|
|Air Temperature (C):||10||6||2||-2||-6||-9||-13||-18||-22||-26||-30||-34|
- R-values are additive, so you can combine two pads to increase your warmth level.
- Women need higher R-values pads because they have lower body mass than men. An additional R-value of 1 is usually a good hedge for women and other cold sleepers
Sleeping Pad R-Value Standard
Last year (2020), the outdoor industry rolled out an international and industry-standard R-value test procedure called ASTM F3340-18. This means you can compare the R-values of different sleeping pads made by different manufacturers and know that they’re all using the same test procedure to measure the R-values of their pads. That’s a huge benefit for consumers and will eventually have the same impact that the adoption of standardized sleeping pad temperature ratings had for comparing sleeping bags from different companies.
The companies that have adopted the new R-value sleeping pad standard (ASTM F3340-18) and retested all of their current sleeping pads include:
- Big Agnes
Klymit has also indicated that they will adopt the new sleeping pad R-value standard but has only listed one pad on their website with an ASTM F3340 rating. For details about the status of industry adoption, see below.
Sleeping Pad R-Value Comparison
The following table provides a side-by-side comparison of the ASTM F3340-rated sleeping pads available in the US market. The pad weights listed are sized for 72″ long x 20″ wide pads, though there are a few exceptions below. The R-Value of a pad remains the same if you select a longer, shorter, or wider variation of the pad.
Status of Industry Adoption
The adoption of the new R-Value standard was driven by REI, which requires that the sleeping pads listed for sale on its main website have an ASTM F3340-18 R-Value rating. However, that’s not the case with sleeping pads listed in the REI OutLet or REI Used Gear sections of their website.
Many sleeping pad companies have still not adopted the new ASTM F3340-18 sleeping pad R-Value standard and it’s not clear that they ever will. In fact, many manufacturers don’t test their pads at all, but “estimate” the R-values of their sleeping mats and pads. In the absence of a standard definition and test procedure, it’s hard to tell if their estimates are accurate or whether they’re comparable to those produced by the standard ASTM F3340-18 R-value testing protocol.
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