Sleeping pad R-value calculator
- Target: a pad (or stack of pads) totalling R 2.5 on the ASTM F3340 scale
- R-values add: a closed-cell foam pad (about R 2) under an inflatable raises the total by that much
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Car camping pads and cots
Every price below is the live Amazon listing price when this page was built; prices change often.
TaskStar 4" Self Inflating Sleeping Pad for Camping with Pillow$49.99Check priceSpec sheet
Heavy Duty Camping Cot for Adults$75.99Check priceSpec sheet
Suteck Camping Cot$89.99Check price
HABUTWAY Camping Cot with Mattress$129.99Check priceSpec sheet
REDCAMP 2 Person Folding Camping Cot for Adults$145.99Check price
Teton Outfitter Camping Cot$199.99Check priceSpec sheet
Exped MegaMat Ultra Sleeping Pad$269.95Check price
Exped MegaMat Sleeping Pad$449.95Check price
How does this calculator work?
R-value measures resistance to heat flow through the pad. Since 2020 most major brands test to the ASTM F3340 standard, so an R 4 from one brand is comparable to an R 4 from another, which was not true before.
The ground pulls heat out of you far faster than air does, and your sleeping bag insulation is crushed flat underneath you, so the pad does nearly all the work below you. The bands here follow the common guidance: under R 2 for summer, R 2 to 4 for three seasons, R 4 to 5.5 around freezing and above R 5.5 for winter.
A cot adds about R 1 to the requirement because air moves freely beneath it. Cold sleepers add another 1. Warm sleepers can take half a point off.
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Keep planning
Frequently asked questions
What R-value do I need for car camping?
For most spring to fall car camping with overnight lows in the 40s, an R-value of about 3 is enough. If you camp into the shoulder seasons or at elevation where lows hit freezing, aim for R 4 to 5. Car campers can carry thick pads, so there is little reason to buy below R 3 unless you only camp in summer heat.
Is an air mattress warm enough for camping?
A standard queen air mattress is comfortable but insulates poorly, roughly R 1 or less, because the large air chamber circulates and cools. Below about 50F it feels cold from underneath. Laying a foam pad, a self-inflating pad or a thick wool blanket on top of the mattress, under your bag, fixes most of it.
Can I stack two sleeping pads?
Yes, and R-values add. A closed-cell foam pad around R 2 under a self-inflating R 3 pad gives roughly R 5. Put the foam pad on the bottom so it protects the inflatable from punctures. Stacking is a cheap way to extend a summer pad into cold nights without buying a new one.
Get the car camping checklist
One printable page: the full packing checklist plus our three complete setups with current prices. No sales sequence.
Used only to send the list. You can also read every setup free on this site.Researched guidance, not professional advice. Figures are published specifications or clearly labelled conventions; check your own gear's manual and your campground's rules.