Sleeping pad R-value: Know how to stay warm

Sleeping Pad R-Value

Table of Contents

When I first got into backpacking and the outdoors, I first obsessed over tents, backpacks, and sleeping bags. I would spend hours researching and combing through the technical details and specs of different products.

So for my first backpacking trip, I had an awesome tent, a lightweight backpack, and a sleeping bag that was rated below the temperatures I was expecting at night.

Lo and behold, I remember waking up in the middle of the night cold and uncomfortable, having a hard time getting back to sleep. I tried putting my jacket on, and then every layer I had with me. Nothing seemed to take away that chill I was feeling, though.

Maybe this whole backpacking thing isn’t as fun as it looked on paper, I thought. In hindsight, I later realized that getting the cheapest sleeping pad I could find wasn’t the way to go.

Learning about R-values and how sleeping pads work with the rest of your sleep system allowed me to fully experience the joy of backpacking and being outside.

Zion National Park

What is R-value?

Imagine trying to compare the softness of bedsheets without thread counts. Every brand claiming that their sheets are the softest, but with no standard measure to compare that claim against. It would be impossible to objectively know how soft a set of sheets was before purchasing it.

R-value serves as the way to measure sleeping pads’ insulating abilities. (technically it is a measure of heat resistance and is used for other items like house insulation) If you were to lie down with nothing between you and the ground, your body heat would transfer to the cold ground. Sleeping pads (or anything with an R-value) help you retain some of your body heat.

heat lost without sleeping pad

This measurement has been standardized across the industry, and it makes it easy to compare across brands. Sleeping pads with higher R-values provide more insulation than those with lower.

Why is R-value important?

Without a sleeping pad, your body heat would be lost to the ground, making for a very cold (and uncomfortable) night. A sleeping pad provides a layer of protective cushioning and a thermal resistance barrier between you and the ground.

That layer of thermal resistance is crucial to staying warm throughout the night. Sleeping bags alone cannot keep you warm. In fact, they need an additional insulating layer to be comfortable at their temperature rating. (which is likely why you feel most sleeping bags are not as warm as the manufacturer says)

cold at night

Having a standard measurement system allows campers to confidently compare products across multiple brands.

Prior to 2020, there was no consistent R-value test across the outdoor industry. Some brands did in-house testing, while others simply provided temperature ratings. Nowadays, the guesswork is out of it because all major brands follow ASTM F3340-18. This standardized testing procedures across the industry and gave customers an easy way to compare products across different brands.

What R-value is right for me?

The answer depends on the conditions that you are using it in and if you have anything else you are using for insulation.

To start, taking a sleeping pad with an R-value of 1.5 for winter camping makes no sense. Even with a warm sleeping bag, you will still be cold.

adding r-values

My general rule of thumb is to have a 3.0-5.0 R-value for a three-season sleeping pad. With a properly rated sleeping bag, a pad in this range should be comfortable down to around 40 degrees. Depending on how many layers you wear and how low your sleeping bag is rated to, you may be good down to about freezing.

Below freezing (32 degrees) you will want a sleeping pad with an R-value above 5.0. That is in addition to some warm clothing layers and a quality sleeping bag. Another technique is to have a foam sleeping pad to place beneath your air pad.

Since the R-values of items add up cumulatively, you can generate a lot of insulation by using multiple sleep pads.

How is R-value measured?

It sounds complicated, but the way the R-value is measured is rather simple.

measuring r-value
  • The sleeping pad is placed between two metal plates with constant pressure. (one hot and one cold)

  • The hot plate is heated to simulate body heat, while the cold plate simulates the cold ground. (95 degrees Fahrenheit and 41 degrees Fahrenheit, respectively)

  • The pad’s R-value is determined by the amount of energy needed to maintain the temperature of the hot plate.

The more energy needed to maintain the warm temperature, the lower the R-value and vice versa.

R-values of common sleeping pads

Sleeping Pad Name

Weight

R-Value

Usage

14 oz.

2.0

Warm weather backpacking

OR

as supplemental pad in cold weather

1 lb. 1 oz.

4.5

Three-season backpacking

8.8 oz.

2.3

Ultralight backpacking

4 lb.

6.0

Cold weath camping

1 lb. 6 oz.

3.8

Three-season backpacking

1 lb. 14 oz. 

7.1

Cold weather backpacking

2 lb. 11 oz.

7.8

Cold weather camping

2 lb. 4 oz.

4.8

Three-season camping

1 lb. 5 oz.

2.9

Lightweight backpacking

12 oz.

2.2

Warm weather backpacking

OR

as supplemental pad in cold weather

1 lb. 1 oz.

2.5

Lightweight backpacking

1 lb. 7 oz.

1.8

Warm weather backpacking

1 lb. 9 oz.

1.5

Warm weather backpacking

1 lb. 3 oz.

8.5

Cold weather backpacking

10 oz.

1.9

Warm weather backpacking

OR

as supplemental pad in cold weather

1 lb. 6 oz.

3.2

Three-season backpacking

2 lb. 2 oz.

4.1

Three-season camping

1 lb. 10 oz.

3.7

Three- season backpacking

1 lb. 3 oz.

4.2

Lightweight backpacking

1 lb. 14 oz.

4.5

Three-season backpacking

FAQ

A sleeping pad R-value between 3.0 and 5.0 will satisfy most three-season camping trips. If you plan to do some cold-weather camping, look for something greater than 5.0.

Yes, there are a couple of easy ways to do this.

  • Layer up your clothing

  • Utilize two sleeping pads (I.e., one closed-cell foam pad and one inflatable pad)

R-values add up, so using a foam pad with an R-value of 2.0 with an inflatable pad with a rating of 3.0 equals a total of 5.0.

No. If anything, your sleeping pad will have an impact on the effectiveness of your sleeping bag. The temperature rating of your sleeping bag requires an adequate sleeping pad R-value to reach its full potential.

Yes. Most brands now follow a standard testing procedure. This allows you to easily compare ratings across multiple brands.

Conclusion

It is easy to fall into the thinking that all sleeping pads are basically the same, they make sleeping more comfortable, right?

Yes, they do indeed make sleeping more comfortable when you are camping. But having a poor sleep pad can have even the most eager backpacker looking for the quickest way off of the trail. (I can attest to that)

My first backpacking trip was derailed because I thought I knew more than I did and thought I was fully prepared. (I was not fully prepared)

Don’t let that be you, and make sure that you are getting the most out of and actually enjoying your outdoor adventures!

sequoia trees

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