Sleeping Bag Temperature Rating

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Choosing the best sleeping bag can be a challenge because there are so many things to take into consideration. One of the most important is the bag’s temperature rating. You need to know when you’re investing in a sleeping bag, whether it will be suitable to the climates in which you choose to camp. You also need to consider your personal preferences when it comes to keeping warm overnight.

Here are a few tips on using a bag’s temperature rating to help you choose the best sleeping bag.

What Is a Sleeping Bag Temperature Rating?

Before you begin shopping, you’ll want to gain a basic understanding of what sleeping bag temperature rating means. If you were to buy a bag with a temperature rating that seems appropriate only to find yourself freezing overnight while camping or sweating like crazy in a bag much warmer than you thought you needed, you aren’t alone. Temperature ratings can be confusing and make purchasing a bag a more complicated experience than it needs to be.

In the past – the not so distant past the temperature rating on a sleeping bag was the best guess of the manufacturer. They’d consider the warmth of the bag would be for the average person and base the rating system on that. Justly subject.

After all, who is the average person? Is he or she a hot or cold sleeper? Where will he or she be sleeping? Will the bag be paired with blankets or a sleeping pad? Mostly, choosing a sleeping bag and having it offer the right degree of warmth was a guessing game for consumers.

The first thing you need to determine is whether you are a hot or old sleeper. Someone who is a warm sleeper usually sleeps without any blankets and maybe without even a sheet. They give off significant body heat throughout the night, and they often make their sleeping partners uncomfortable. If the house temperature is set at 65 degrees or more, they are perfectly comfortable sleeping with very little covering.

A cold sleeper, on the other hand, tends to sleep with many blankets, even in a 65-degree room. Even with pajamas and blankets, they tend to wake up cold. This occurs because they have slow metabolism while sleeping, and their bodies produce very little heat overnight.

If you aren’t sure if you are a hot or cold sleeper, pay attention throughout a few nights to your sleeping habits and see if you can figure things out. Usually, within a night or two, you’ll have an idea for whether you are a hot sleeper, a cold sleeper, or somewhere in between.

women laying on a pad outside

The EN 13537 Sleeping Bag Temperature Rating

To eliminate the subjective nature of rating sleeping bags, Europe came up with the EN 13537 testing method. It standardized the testing and rating of sleeping bag warmth and made it easier for consumers to determine which sleeping bag would best suit their needs. The United States has since adopted the rating system since it was first introduced in 2005.

The system divides sleeping bags into several different categories, including:

  • Extreme. Sleeping bags meant to be used to prevent death from hypothermia in the coldest possible temperatures. The rating is based on use by an average female over six hours. As the name implies, these sleeping bags offer the most warmth in the most extreme cold conditions.
  • Sleeping bags that allow an average male sleeper to be warm for up to eight hours curled up without moving.
  • Sleeping bags that keep the average female comfortable in a relaxed position for no specific period.
  • Upper. Sleeping bags that keep an average male comfortable and do not cause excessive perspiration while sleeping. It is assumed the sleeper will not fully zip the bag and will sleep with his arms out from undercover. This type of bag provides the least amount of warmth.

How are Bags Tested within the EN 13537 Rating System?

You might be wondering how the EN 13537 test works considering monitoring the use of a sleeping bag can still be pretty objective depending on who is conducting the analysis or who is the subject of the test.

The testing system wanted to be as objective as possible, so testers utilize a heated mannequin in a hat and clothed in thin thermal underwear. Mannequins are placed in the bags, and then the bags are placed on top of a lightweight sleeping pad. Mannequins feature sensors to alert testers to any changes. The dummy, bag, and pad are put into a cold box, and the loss of heat is measured through the sensors. Testing establishes a baseline for loss of heat that allows consumers to compare sleeping bags to each other.

But what about hot sleepers versus cold sleepers? Even with the testing system, it can still be challenging to determine what sleeping bag temperature rating is right for you when it comes to using the bag under real-world conditions.

This is why it’s so important to understand whether you are a hot or cold sleeper. Cold sleepers tend to need bags that provide warmth in colder temperatures, even if they aren’t camping in colder temps. They should err on the side of choosing warmer bags. Warm or hot sleepers should choose bags that offer some warmth, but that is more in the lower range and don’t overheat sleepers.

hiker choosing sleeping bag

Other Considerations When Choosing a Sleeping Bag

In addition to the temperature rating and the type of sleeper you are, there are a few other things to consider when shopping for a sleeping bag.

For instance:

  • Consider what type of sleeping pad you intend to use. Thicker sleeping pads, especially if they claim to insulate your body heat, will allow you to choose a sleeping bag with a lower rating in terms of warmth.
  • Whether or not your tent is well-insulated – or if you will even be using a tent – is another important consideration.

Sleepwear and pajamas can add additional warmth, but if you are more comfortable sleeping sans clothing or in thin clothing that doesn’t cover a great deal of your body, you’ll want to bump up the heat rating on your sleeping bag.

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