If you have ever had a conversation about sleeping pads, chances are that someone brought up the ‘R’ word.
Yep, we’re talking about the R-value.
If you have ever found yourself wondering, “What is R-value? Why is it a big deal for sleeping pads?”, then this is the blog for you.
By the end of this article, you’ll know exactly what sleeping mat R-value means, why it matters and what rating you will need. Ready? Let’s dive straight in!
What is R-value?
R-value is a scientific measure of thermal resistance based on principles of thermodynamics and heat transfer. It can be used to calculate any material’s ability to resist the transfer of heat. The greater the thermal resistance of any given object or material, the more insulative it will be.
When used to describe a sleeping mat, the R-value indicates its ability to insulate you from the cold ground. The higher the R-value of your sleeping pad, the better it will be at keeping you warm. For example, a sleeping mat with an R-value of 4.0 will retain more heat (and keep you warmer) than a sleeping mat with an R-value of 1.0.
Your camping mat must provide enough insulation to counteract the cooling effect of the ground drawing heat away from your body. And, the R-value provides a standardised measurement to gauge how effective your sleeping mat will be at low temperatures.
Making sense so far? Great!
Why does sleeping mat R-value matter?
The R-value is THE most important factor to consider when choosing a sleeping mat.
Why?
Easy. If the R-value rating of your sleeping pad is not high enough, and therefore insulative enough, for the conditions, you’ll be cold and miserable, all night long.
When you lie on a sleeping mat, your body heat naturally conducts to the cool surface of the ground beneath you. Even in mild climates, the ground is often much colder than the air, leading to significant heat loss. Without adequate insulation, this causes you to lose body heat quickly.
In mild climates, this would cause you to feel cold and uncomfortable throughout the night. But, in cold environments, not having enough insulation could cause you to develop hypothermia, which can be life-threatening.
What sleeping mat R-value rating do you need?
The specific R-value rating that you need for a sleeping mat will depend on three main considerations.
Let’s go through each of these in detail.
External Conditions
Here are the recommended R-values for different weather conditions.
R-Value 0.5 to 2.0 – Warm
A sleeping mat with an R-value of 1.0 to 1.5 is going to be ideal for warm weather conditions where the temperature does not drop below 10º overnight.
R-Value 2.0 to 3.5 – Cool
Camping mats in this category are great all-rounders because they can be used for anything from warm summery weekends away to chilly autumn adventures. An R-Value of 2.0 to 3.5 will be sufficient to keep you warm in temperatures as low as 5º.
R-Value 3.5 to 5.0 – Cold
If you are camping in cold conditions where the temperature is guaranteed to drop to freezing (or even just below it) overnight, then you will need a sleeping mat with an R-value in the 4.0 to 5.0 range.
R-Value 5.0+ – Extreme
For adventurers who camp in high-altitude or arctic environments, a sleeping mat with an R-value over 5.0 is advisable. These highly specialised camping mats feature specific technology that increases warmth and heat retention, such as built-in heat-reflective foil or closed cell foam.
Individual Differences
Your metabolic rate, body composition, circulation and hormones can all affect how much heat your body generates, and how warm you feel while you sleep. And, all of this has a significant impact on what sleeping mat R-value you will need.
Warm Sleeper
Depending on just how hot you run, you might want to consider going for a camping mat on the lower end of the suggested R-value ratings for each temperature category.
Cold Sleeper
Always find yourself getting cold at night? Go for the higher end of the recommended R-value, or even the low end of the R-value ratings for the next warmth category up.
We’ve put together this chart to show you what R–value rating you should go for, based on whether you are a warm or cold sleeper.
Sleep System Setup
Last but not least, your sleep system setup will influence your camping mat R-value rating requirements.
Your ‘sleeping system’ includes everything else that goes into your setup for sleeping outdoors, from the shelter type, such as a hut, tarp or tent, to your sleeping bag, along with any extra items such as a sheet or liner.
Here are a couple points to consider when choosing the best sleeping mat r-value for your complete sleep system:
You can use a high R-value sleeping mat in warm weather.
A sleeping mat with a higher R-value (3.0+) will feel warmer compared to a sleeping mat with a lower rating because it retains the heat your body radiates. This doesn’t necessarily make you hotter, but it does help to keep your body temperature consistent as you sleep.
By comparison, a low R-value camping mat (0.5–2.0) will feel cooler to sleep on in warm weather because it allows the heat from your body to dissipate away into the ground, instead of trapping it inside the mat. However, some Extreme (R-value 5.0+) camping mats with heat-reflective technology are designed to redirect warmth back to your body, which could cause you to be uncomfortably warm if used in warm conditions.
Your sleeping bag and your sleeping mat need to work together.
A common mistake people make when camping in cool or cold conditions is relying solely on their sleeping bag for warmth.Your sleeping bag cannot make up for a sleeping mat that doesn’t have a high enough R-value for the conditions.
A sleeping bag provides warmth because the lofting filling retains the heat given off by your body. Anywhere that it is compressed, such as underneath you, the insulative properties of your sleeping bag are significantly diminished.
So, without adequate insulation beneath you, all your hard-earned warmth will just dissipate away into the ground – no matter what warm rating your sleeping bag has.
Your sleeping bag and camping mat work together to form the foundation of your sleeping system, so it is essential that both these items are warm enough for conditions you’re camping in.
Now you know what sleeping mat R-Value is!
Now you know all the fundamentals of sleeping mat R-value.
By taking the time to read this article, you should now have a solid understanding of how R-value works, why it is important and how to choose the best sleeping mat R-value for your needs. If you have any other questions, don’t hesitate to send us an email or DM on Instagram, we’re here to help.
