Hi everyone, I'm helping to organize an adventure trip and am recommending clothing to some of the travelers.  I always struggle when trying to recommend one piece of clothing as warmer than another.  Is anyone aware of any brands that have a warmth rating system or any way to determine which jackets and pants are warmer than others?



Hi @Matt1 , wow, that's a huge, broad area, so many layers!

And speaking of layers,.....It all boils down to the temps and conditions of the trip.  You only said 'adventure trip', so is that scuba diving? or sky diving?, Ice climbing?

Warmth is created by trapping dead air next to the skin.

To keep this air warm next to the skin, depending on the outside air/wind, requires layering.

I think it's important to understand how we lose warmth to understand the ways of preventing it.

The body loses heat through:*

  • Evaporation of water from your skin if it is wet (sweating). If your clothing is wet, you will also lose some body heat through evaporation and through respiration (breathing) when the body temperature is higher than 99°F (37°C). During intense exercise, the body loses 85% of its heat through sweating.
  • Radiation (similar to heat leaving a woodstove). This normal process of heat moving away from the body usually occurs in air temperatures lower than 68°F (20°C). The body loses 65% of its heat through radiation.
  • Conduction (such as heat loss from sleeping on the cold ground). Heat is lost in air temperatures lower than 68°F (20°C). The body loses about 2% of its heat through air conduction. However, water causes more heat loss from the body than air does, so heat can be lost from the body very quickly when it is placed in cold water.
  • Convection (similar to sitting in front of a fan or having the wind blow on you). The body loses 10% to 15% of its heat through convection.

(*from Mott Children's Hospital)

the point being, that one needs to 'layer-up' to keep the warmth trapped in. 

Sometimes you need lots of layers, thermals, pile, down.

Sometimes you only need a wind-shell to keep the wind from making you cold.

But, there's lots more, like guarding against the  building up of moisture/sweat from the inside, overheating, and losing warmth through wet clothing (conduction), recognizing and taking action to prevent hypothermia.

Anyway, this all leads back to the clothing, layer by layer: thermals, base layer, insulating layer(s), and circling back around, what are the conditions you expect? 

We need to 'layer' for the environment we're going into.

But to answer you question directly, I don't think most clothing has a 'warmth' rating, as do sleeping pads.  Take down jackets for example, they range from a lightweight variety (summer/shoulder seasons), to those suitable for the Himalayas, but a buyer has to more or less deduce which jacket would be best.  I think there are plenty of gear testing sites, which I used, when I was searching for a 'max warmth' down jacket.


REI Member Since 1979 YouTube.com/philreedshikes

Hi @Matt1!

@Philreedshikes gave a great response here. 

I just want to add that while products like sleeping bags and sleeping pads do have a consistent, uniform rating system to describe their warmth, clothing does not. Anytime you see a warmth rating on clothing, it's generally manufacturer specific, and a general estimate based on in-house tests. 

That being said, there are some consistencies in clothing. For example, down fill power refers to the measure of down quality, or "fluffiness" related to the insulating power of the down. So 800 fill down will be warmer and lighter than 400 fill down if the same amount of down is used. However, there is no standard as to how much down should go in a garment, and any place where the garment has baffles (stitches or welds) to keep the down in place, there is no fill. This means that if a garment has a lot of baffles, it might be less-warm. (This is why some down jackets have many baffles in places where the body dumps lots of heat, like armpits). 

3M makes a synthetic material called Thinsulate which is used by many manufacturers for glove and boot insulation, and is rated in terms of the amount of grams of weave per square meter, typically anywhere from 100-400g. As the rating goes up, the warmth goes up. Yet there is no comparable equivalent rating among other types of synthetic insulation used in gloves and boots, and there is no standard for how the insulation is actually used in clothing. So, the warmth remains pretty subjective.

Frustrating, right? Ultimately, as Phil explained, the environment, a person's personal cold tolerance, and the activity all play a huge part in choosing the right clothing. The most important way to dial in warmth in consideration of those factors is layering. By layering, you can dial in an appropriate warmth for conditions.

Check out these Expert Advice articles on choosing insulated outerwear, and what to wear backpacking for more on clothing and layering.

Hope this helps!

At REI, we believe time outside is fundamental to a life well lived.

Thanks Philreedshikes and .

I'm a little familiar with comparing weight and type (synthetic vs different lofts of down) of insulation in clothing.  I was looking to see if any apparel manufacturers have a rating system just to show which clothing is warmer than others, not necessarily a recommendation for a certain temperature range.  I haven't found anything like that and it sounds like you two haven't either.

Thanks again.