Last Updated on 30/09/2022
Want a quick and easy guide to sleeping pad R-values?
We combined the research of several large sleeping pad manufacturers to create this sleeping pad R-value chart. You will see how the R-values of sleeping pads convert into Fahrenheit and celsius temperature ratings based on what we found.
R-values are ratings given to insulation layers to provide an estimate of the thermal resistance (the R stands for Resistance). It is calculated by dividing the thickness of the insulation in inches by the thermal conductivity. It all gets a bit complicated the further you go into it so we will leave that to the experts.
In this guide, we want to focus specifically on insulated winter sleeping pads. The R-value rating system for sleeping pads has only become standardized in the past decade and before that companies could pretty much say whatever they wanted as no one was checking. Nowadays R-values are actually pretty accurate and can be used as a reliable specification to base decisions from.
Sleeping Pad R-Value Chart
Here is the Sleeping Pad R-Value chart we made to estimate the season rating and temperature range of individual camping mats. This is based on multiple reputable sources (linked further down) and should give you at the very least, a good guide to R-value temperature ratings.
|R-1||2 SEASON||50° F||10° C|
|R-2||2-3 SEASON||40° F||4° C|
|R-3||3 SEASON||30° F||-1° C|
|R-4||3 SEASON||25° F||-4° C|
|R-5||4 SEASON||20° F||-7° C|
|R-6||4 SEASON||0° F||-18° C|
|R-7||4 SEASON+||-20° F||-28° C|
|R-8||4 SEASON EXTREME||-38° F||-36° C|
Sleeping Pad R-Value in Celcius and Fahrenheit
We researched as much as we could about the R-values of sleeping pads to try and get the most accurate conversions into Fahrenheit and Celcius units. You can use this chart to check how warm your sleeping bag is and whether it is suitable or not to camp in cold weather.
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Sleeping Pad R Value Chart Season Ratings
Understanding which R-value sleeping pads are designed for which seasons is perhaps an easier way to think about warmth. If you only camp in the summer months then you can enjoy the benefits of a lightweight and low R-value sleeping pad without ever feeling cold. If you know you are going to be camping in freezing winter weather then you can look for sleeping pads that are above an R-value f 5.
Here is how we would rate each level of insulation in terms of seasonal use:
- R-VALUE 1 = 2 SEASON
- R-VALUE 2 = 2-3 SEASON
- R-VALUE 3 = 3 SEASON
- R-VALUE 4 = 3 SEASON
- R-VALUE 5 = 4 SEASON
- R-VALUE 6 = 4 SEASON
- R-VALUE 7 = 4 SEASON+
- R-VALUE 8 = 4 SEASON+ EXTREME
What R-Value should you use for winter camping? We recommend using a sleeping bag with an R-value of around 5 when you are camping in below-freezing temperatures in winter.
Is a Higher R-Value Sleeping Pad Worth It?
The higher the R-value of a sleeping pad is, the warmer it will be. It will also likely be more expensive.
As you can see in the chart above, a sleeping bag with an R-value of 2 is great for lightweight backpacking and summer camping but will not keep you very warm in winter. But if you are camping in an Alaskan winter at -20 degrees then you need to look for an R-value 8 sleeping pad to be on the safe side.
If you cherish your comfort and can afford it then getting a higher R-value sleeping pad is absolutely worth it.
What is the Highest R-Value Sleeping Pad?
The highest R-value sleeping pad we could find was the Exped Megamat Max 15 which has an incredible 10.6 R-value. This will keep you warm down to an almost unimaginable -54 degrees Fahrenheit.
Compare that with an air mattress that has no insulation and an R-value of between 0 and 1 and you will almost immediately notice the difference.
What Does Thermarest Say About Sleeping Pad Temperature Ratings?
Thermarest is one of the biggest authorities in the sleeping pad space. Unlike most other brands, Thermarest specialized solely in sleeping mats before eventually branching into sleeping bags and other product ranges. This means they have done maybe the most research and development and so have some incredible insights into the R-rating system.
They have several articles explaining things like what R-value means, comparing R-value to temperature ratings, and breaking down the ASTM R-Value standard. Here is a summary of how they chart the R-value of their sleeping bags:
- Thermarest has an onsite testing facility that uses two giant metal plates to determine accurate readings of thermal resistance
- One of the plates is a sensor while the other provides a constant temperature
- The way the machine works is by measuring how much energy it takes to maintain that steady temperature
- This reading is then inputted into an equation that provides an accurate R-value
- They also consult with thermal science engineers to ensure they stay up to date with inovation
And here are some other facts we found interesting:
- Sleeping bags use insulation to keep cold air out and circulate warm air while camping pads work differently. Pads need to create thermal resistance to prevent your heat from transferring into the ground.
- Sleeping bags are rated differently using and EN rating system while sleeping pads use the ASTM R-value system
- Thermarest was directly involved, along with other companies, in creating the standardized ASTM R-value system
What Does Exped Say About Sleeping Pad Temperature Ratings?
Exped makes the warmest backpacking sleeping pads in the world and they have a very brief guide on their website. The key takeaways are:
- Use R-value 0 – 2 sleeping pads for 2 seasons, warm weather camping (50° F)
- Use R-value 2 – 3.9 sleeping pads for 3 seasons, cool weather camping (32° F)
- Use R-value 4 – 5.4 sleeping pads for 3-4 seasons, cold weather camping (20° F)
- Use R-value 5.5 – 8 sleeping pads for 4-season, extreme cold weather camping (0° F)
We hope this guide and sleeping pad R-value chart helped you to wrap your head around what the number means and how you can use it to make good decisions.