Sleeping pads look like mattresses for monks or poor swimming pool floats. Thus, for campers with plenty of packing space, many forego these thin pads and sleep on air mattresses or cots. But while sleeping pads do add comfort, that isn’t their primary purpose; they are insulation.
Sleeping pad R-values reflect its level of insulation. Therefore, the R-value is not a comfort rating regarding how cushy and soft it makes the ground feel. Instead, it indicates how warm it will keep a camper by preventing heat transfer from you to the ground.
The cold, hard truth is that sleeping bags can’t keep all of your body warm. So even the most comfortable hammock needs an underquilt or sleeping pad to prevent the dreaded “Ice-butt.” But there is no underquilt for people on the ground; instead, there is your tarp (footprint), tent floor, and sleeping pad.
Want to find out more about a sleeping pad r value? Read on!
Why Do Sleeping Pads And R Values Matter?
Sleeping pads are the camper’s equivalent of a knight’s shield, fending off the cold. Some sleeping pad “shields” are the equivalent of tin, and others are the equivalent of Captain America’s vibranium shield. The former can be perfect for summer, and the latter helps alpinists and winter campers beat the season.
A sleeping pad is necessary regardless of the quality of your sleeping bag. Sleeping bags work by creating an insulating air pocket. However, there is no air pocket wherever the sleeping bag is being compressed. Thus, the part of your body, usually the back, that is sleeping against a surface is not being kept warm by your bag.
So, when sleeping on the floor of a tent, the ground is conducting heat away from your body. Thus, you, the living and breathing creature, keep the earth warm by “feeding it” your body heat.
When sleeping in a hammock, a similar situation occurs. The air under the hammock is circulating, pulling heat from your body. However, a sleeping pad prevents the air from snatching heat.
Thus, when buying a sleeping pad, there are various features to consider:
- Weight (essential backpacker info)
- Bulk (necessary backpacker info)
- Camping style (best sleeping pad for a tent might be different when in a hammock)
- Ease of use (some require more effort to set up than others)
- R-Value (insulation)
Campers need to prioritize the features when buying a sleeping pad. For example, heavier and bulkier sleeping pads usually cost less than those designed for backpacking. Also, it’s easier and cheaper to make sleeping pads lighter and less bulky if comfort and R-value are not a priority.
A sleeping pad’s thickness, bulk, and comfort will not reflect its R-value. However, there are high-tech sleeping pads that are incredibly thin that will keep you warmer (and possibly more comfortable) than some cheap air mattresses.
The R Value Scale And Its 2020 Update
R-values for sleeping pads work on a scale that begins at 1. The higher the R-value, the more insulation (warmth) the sleeping pad provides.
The rating system is straightforward to understand. Each R-value equals a single layer of warmth. These are virtual layers measured by effectiveness, not thickness.
Thus, a sleeping pad with an R-value of 3 is the equivalent of stacking a pad with an R-value of 1 on top of another with an R-value of 2. It is also possible that your pad with an R-value of 2 is thinner than your pad with 1.
However, until 2020, the R-value system was flawed due to a lack of standardized testing. Thus, like the inconsistencies in women’s clothing sizes, an R-value of 4 in one brand could be a 3 in another. Savvy campers would go on forms to get a feel for a brand’s R-value, but it remained a gamble.
ASTM R-Value Sleeping Pad Standard
In 2020 many outdoor gear manufacturers changed to a single sleeping pad testing method known as ASTM FF2240. The testing method was designed by a pool of experts working for prominent and respected outdoor brands such as REI Co-op and Therm-a-Rest.
The brands that use the ASTM FF2240 sometimes display it by stating it has an ASTM R-value. The change has made it much easier for consumers to buy sleeping pads that meet their needs. Consequently, our below recommendations for which R-value you need are based on the ASTM R-value scale.
Also, remember that you need to select the R-value based on the night conditions of your adventure. For example, when camping in arid areas or high altitudes, the days might be incredibly warm but cold at night.
Lastly, select the R-value for the worst-case scenario for your location and season. You can always wear less in your sleeping bag or leave it slightly unzipped. But trying to fix a cold back or side is difficult, no matter what you wear, if a chilly night rolls in.
A higher R-value sleeping pad will not cause you to overheat. The reason people try to reduce the R-value is to reduce packing weight, bulk, and cost.
- R-Value 1-2 = 50F or warmer
- R-Value 2-3.9 = 32F – 49F
- R-Value 4 – 5.4 = 20F – 31F
- R-Value 5.5+ = 19F or below
R-Value Sleeping Pad By Season
Some websites and manufacturers are terrible at providing consumers with precise information. Thus, rather than provide the R-value of a sleeping pad on the numerical scale, they give it to you by season, much like tents are sold.
Thus, you will sometimes see sleeping pads rated as Summer, 3-season, or 4-season.
The general interpretation of the R-value for these obscure seasonal categories is as follows:
- Summer = R-Value 1-3
- 3-season = R-Value 3.1 – 4.4
- 4-season = R-Value 4.5+
The problem with the system is that there is a vast range in these interpretations. For example, see the chart below to understand a seasonal category’s breadth.
|Sea To Summit Ultralight Air
|Big Agnes Air Core Ultra Sleeping Pad
|Therm-a-Rest NeoAir UberLite
|Sea to Summit Ultralight Insulated
|Big Agnes Q-Core Deluxe
|Therm-a-Rest Trail Pro
|Nemo Tensor Alpine
|Klymit Armored V Rugged
Remember, the differences in the lower number categories might not seem significant, but they can have a substantial impact. For example, an R-value of 2 is double the protection of a pad with 1.
Does A Lounging Pool Float Have R Value?
A lounging pool float will not have an official R-value. However, it would typically be at the lower end of the summer scale. Nor are they recommended as sleeping pads because they are:
- Take ages to blow up
- No back support, despite the bulk
- Loud to sleep on
- No grip, so campers typically slide off them during the night
- Fragile, being easily punctured, or having a seam split
Does Memory Foam Have R Value?
Memory foam’s R-value depends on thickness. So, pieces used for sleeping pads have an R-value ranging anywhere between 1-7 depending on quality and size. However, a thick, memory foam mattress will have an R-value in the double digits.
Memory foam also retains your body heat, a feature that is both positive and negative. On the plus side, the memory foam will not just insulate you from the ground but gradually provide warmth as it absorbs your body heat. It is a bit like a sleeping bag for your back.
However, this positive becomes a negative in higher temperatures. Usually, having a bigger R-value sleeping pad will not cause you to become too warm. But memory foam can contribute to night sweating if you are not careful.
For campers that don’t need to worry too much about bulk and weight, sometimes use a sleeping pad on top of memory foam. The dual-system ensures they are comfortably protected from the ground, while the sleeping pad prevents the foam from absorbing body heat. It is an excellent alternative to using an air mattress.
Do R Values Stack If Sleeping Pads Are Layered?
R-values do stack if sleeping pads are layered underneath you. For example, putting the Klymit Static V (R-Value 4.4) on top of the Therm-a-Rest Z Lite (R-Value 2) will give you an R-value of 6.4. It’s an excellent way to save money when camping in unexpected conditions, so long as bulk isn’t an issue.
Are There Hacks To Increase The R Value Of A Sleeping Pad?
Sometimes you get caught short while camping and discover your sleeping pad isn’t doing the job as well as you need. Unfortunately, while this is excellent information for future adventures, it doesn’t help you get decent sleep for the rest of the trip.
However, rather than weep over the campfire, there are some potential ways to fix the issue, depending on what’s available. It’s all about adding layers between the sleeping pad and the ground. So, look through your equipment and the surrounding area, keeping an eye out for:
- Lots of dry leaves (downside: loud)
- Spare clothing
- Space blanket or emergency blanket (some claim putting it shiny side up helps)
- Spare tarp
- Table cloth
- Trash bags
- Dry newspaper
- Punctured air mattress (yes, even if it is flat, it will still help protect you)
- Dry towels
Can High R Value Sleeping Pad Help A Poor Sleeping Bag?
A higher R-value sleeping pad won’t help a cheap summer sleeping bag. The only possible exception is sleeping on a slab of memory foam. The two don’t boost the other’s job because they keep different parts of the body warm. Using a higher R-value pad with a poorly insulated bag is like needing a better coat, so you pull on a thicker pair of socks. Sure, your feet are toasty, but your core body temp will still be struggling.