Sleeping Pad Efficiency and Packed Size

In a previous post, I discussed the development of an efficiency factor for regular sized sleeping pads that takes into account warmth and weight.  The warmth is given by the R-value, a standard measure used in the construction industry for insulation.  I standardized the weight with the surface area, but I only included a chart with “regular” size pads.  I was asked how well this held up with pads of different sizes.  Well, because the efficiency factor is a function of the surface area divided by weight, it should be able to cope with pads of different dimensions.

Efficiency Update

Just like before, the efficiency factor is calculated such that a lower number is better.  I’ve sorted the chart on that efficiency factor, putting the most efficient at the top.

I put a lot more data into the spreadsheet and I discovered something interesting.  For the most part, smaller pads have a slight advantage.  However, the Exped Downmats and Synmats seem to favor the larger mats.  Perhaps this is because of the valve and pump weight being spread over more surface area.

I also multiplied the original efficiency factor by 1000 to make it easier to read.  This doesn’t actually have any effect on the factor because it is uniformly applied to the original factor.  It simply changes the decimal position.

I plotted the efficiency curve and noticed that it slowly increases and then suddenly goes up quite rapidly.  It looks like the main inflection point occurs somewhere between 6 and 8.

Efficiency is not the only thing that is important though.  One of the big things I look for is how small I can pack the pad.

Packed Size

I really don’t like having things hanging off my backpack.  The streamlined shape of most internal frame packs is ruined when a big pad is strapped to it.  This causes it get snagged on tree branches and brush.  For me, this means I need a very small package that can fit inside my pack.

However, others do use their pads as a frame in ultralight packs.  These folks won’t necessarily care about packed volume as much as the structure and rigidity of the pad when it is in the back of the pack acting as a framesheet.

For this reason, I’ve not tried to create a more unified factor that includes the packed volume of the pad.  Users will have to decide for themselves what is important.

Total Picture

To give a complete picture of these pads, I’ve included the MSRP per the manufacturer or distributor, or if that was unavailable, I used information from REI to fill in the gaps.

Despite being included in the efficiency factor, I’ve included R-value and weight in the chart.

This way you can see better whether a pad fits your needs in terms of weight, warmth, efficiency, packed volume, and cost in USD.

Here is the updated chart:

 Mat Efficiency Pack Vol R-value Weight Cost Exped Downmat 9 DLX 2.74 311 8 44.1 \$ 180.00 Exped Downmat 9 3.00 254 8 34.6 \$ 160.00 Exped Downmat 7 DLX 3.38 216 5.9 40.2 \$ 165.00 Exped Synmat 9 DLX 3.38 423 6 40.9 \$ 120.00 Thermarest Ridgerest Small 3.61 663 2.6 9 \$ 19.95 Exped Downmat 7 3.65 254 5.9 31 \$ 150.00 Thermarest Ridgerest Regular 3.74 1005 2.6 14 \$ 24.95 Thermarest Ridgerest Large 3.80 1418 2.6 19 \$ 34.95 Thermarest NeoAir Small 3.83 77 2.5 9 \$ 119.95 Thermarest NeoAir Regular 3.89 113 2.5 14 \$ 149.95 Exped Synmat 7 DLX 3.89 339 4.9 38.4 \$ 110.00 Thermarest NeoAir Medium 3.94 113 2.5 13 \$ 139.95 Thermarest NeoAir Large 3.95 175 2.5 19 \$ 169.95 Exped Downmat 7 Short 4.00 177 5.9 22.2 \$ 135.00 Big Agnes Insulated Air Core 4.07 177 4.1 24 \$ 79.95 Thermarest Ridgerest Deluxe Regular 4.26 1161 3.1 19 \$ 34.95 Exped Synmat 7 4.29 308 4.9 30.3 \$ 100.00 Thermarest Ridgerest Deluxe Large 4.36 1697 3.1 26 \$ 44.95 Thermarest Prolite Plus Regular 4.39 199 3.8 24 \$ 99.95 Thermarest Z-lite Regular 4.42 550 2.2 14 \$ 39.95 Big Agnes Two Track 2″ 4.49 412 6.5 42 \$ 82.95 Big Agnes Dual Core Large 5.03 596 5 49 \$ 144.95 Thermarest Prolite XS 5.05 78 2.2 8 \$ 59.95 Thermarest Prolite Regular 5.05 145 2.2 16 \$ 99.95 Thermarest Prolite Large 5.19 207 2.2 22 \$ 119.95 Big Agnes Dual Core Long 5.26 431 5 41 \$ 104.95 Big Agnes Dual Core 5.28 367 5 38 \$ 99.95 Thermarest Prolite Small 5.32 100 2.2 11 \$ 79.95 Exped ComfortFoam 7 DLX 5.82 539 4.9 57.5 \$ 105.00 Thermarest TrailLite Regular 5.85 305 3.8 32 \$ 59.95 Thermarest TrailLite Large 5.88 432 3.8 43 \$ 69.95 REI Camp Bed 3.5 Regular 6.35 797 7 80 \$ 99.50 Exped ComfortFoam 7 6.51 339 4.9 45.9 \$ 85.00 REI Trekker 1.75 Regular 6.61 376 4.2 40 \$ 64.50 REI Camp Bed 2.5 Regular 7.65 617 4.5 62 \$ 75.50 Zotefoams Evazote Winter 7.73 2.06 18.5 \$ 33.30 Big Agnes Sleeping Giant 8.53 565 3.5 43 \$ 64.95 Big Agnes Clearview Air Pad 10.42 49 1 15 \$ 49.95 Big Agnes Air Core 15.28 100 1 22 \$ 49.95

2 Responses to “Sleeping Pad Efficiency and Packed Size”

1. Chris says:

Thanks Lawson. Glad you are enjoying my blog.

2. Chris,