What do the sleeping bag ratings mean for male and female sleepers? Are they tested?

Confused about sleeping bag temperature ratings? Here's what they mean, how they're tested, and how to choose the right bag for your needs based on your sleep style and gender. A few definitions to start:

• Comfort Rating = the temperature rating a female sleeper should orient themselves with

• Lower Limit = the temperature rating a male sleeper should orient themselves with

• ISO 23537 = Sea to Summit bags (like most quality sleeping bags) are tested in certified laboratories for temperature rating according to this test. 

• R-Value = a measure of how well a sleeping pad insulates you from the ground.
  
  

Published Ratings

Before we get to the details of the testing, one continual source of confusion is the difference between the Lower limit and the Comfort Rating for any given sleeping bag:

• The Lower limit of a sleeping bag should be used as a guide* for male sleepers
• The Comfort Rating of a sleeping bag should be used as a guide* for female sleepers
  
  

In the case of the Unisex Spark 15°F / -9°C

• the Lower limit is 15°F / -9°C which is what a male sleeper should use for orientation*
• the Comfort Rating would be 29°F / -2°C which is what a female sleeper should use for orientation*
  • So, a female sleeper purchasing this Unisex sleeping bag can think of it as a "Spark 29°F"

Due to misconception, some sleepers may opt for a Unisex bag over a Women's Specific bag, thinking it will offer the same warmth in a lighter package – this is not the case. 

The Women's Spark 15°F / -9°C has the following ratings:

• the Lower limit would be 5°F / -15°C - which is what a male sleeper should use for orientation*
• the Comfort Rating is 15°F / -9°C - which is what a female sleeper should use for orientation*

Why the asterisks above?

Because the 'Lower Limit' and Comfort Rating' are not guaranteed temperatures; they are guidelines.

Different people perceive cold differently. A male sleeper who 'sleeps cold' may care to use the 'Comfort Rating' rather than the 'Lower Limit' as an indication of the appropriate sleeping bag for his use.

Because the published temperature ratings require a sleeper to use a sleeping pad with adequate insulation, and be dressed in appropriate clothing. (Please see the 'How sleeping bags are tested' below)

All Sea to Summit Unisex sleeping bags are listed using the LOWER limit, which is appropriate for male sleepers. All Sea to Summit Women's Specific sleeping bags are listed using the COMFORT rating, which is appropriate for female sleepers.

Both comfort and lower ratings are listed on every Sea to Summit sleeping bag's website page under "tech specs". 

How sleeping bags are tested to the ISO standard

The test is conducted using a heated manikin inside the sleeping bag in a cold chamber. Measurements are taken to determine how much warmth the sleeping bag retains. The manikins are dressed in Expedition Weight base layers with an insulating cap and the sleeping pad used has an R-Value of over 5.

Without meeting the above requirements, your sleeping bag will not achieve the published rating. This is true regardless of metabolism or other factors.

Need help with a sleep system recommendation? Please reach out to us here and we'll be happy to help.