Temperature Rating

My goal with Timmermade sleep systems was for the rating to land in the range of comfort rated for average sleepers. As an ultralight builder, keeping sleepers warm is the primary goal, but not the only goal. I also want a rating system that allows for people to dial in a system that provides the level of insulation they need for the temperatures they expect to sleep in without weighing them down with more than they need. Centering the rating over the average sleeper was the best method for achieving this. Cold sleepers would adjust down the ratings accordingly and warm sleepers would adjust up the ratings accordingly. Anyone who wanted a cushion for the unexpected would adjust down the ratings accordingly. Anyone who wanted to add clothing layers to their system for warmth would adjust up the rating accordingly. Feedback is a huge component to finding this point and I received almost entirely good results that indicated I was hitting this target. However, these rating are extremely subjective and the temperature that different people sleep at is highly variable. People have different experiences that create different perspectives on how one’s temperature is in comparison to other’s. Someone may come from general mass market products thinking they are an average sleeper, to cottage industry ultralight items and find out they are actually very cold sleepers in this different market. From a business perspective and from a safety perspective it is less risky to over insulate than to try to fine tune an average level of insulation and have a single person find out they aren’t warm enough. On 5/19/2021 I decided to bump the calculated loft, baffle height, and fill weight up by a very large margin on all Timmermade box baffled sleep systems in an effort to hit a new target of at least comfort rated for most everyone.

It is still my goal to provide a rating system that allows for fine tuning for the weight conscious. Only now, I am setting the default at a higher level of insulation to cover everyone and asking the knowledgeable, weight conscious to adjust accordingly. In an effort to inform those who wish to adjust I will provide all the previous chamber calculations and the new calculations. Additionally, when looking at the systems on their product pages, each selected variation will now display every available metric that is useful for comparison.

The changes that were made will be shown as calculated loft. Calculated loft is a useful metric for the consumer as it is a basic chamber fill calculation. When a builder is filling each chamber of a system they take the length x the width x height (calculated loft) and divide by the fill power. The result is the amount (ounces) of down in that defined area. If the consumer is provided with the fill power and the calculated loft (height), they now can know the exact amount of fill weight in their system, whether that be in a selected chamber, a selected area of it, or in the whole thing. It is a reliable metric for comparing warmth regardless of other variables like size, taper, or features. Total fill weight in a whole system is an amount that is subject to many variables, which is unreliable at best and often deceiving. A sleep system that is well fitted with the same chamber calculations as one that is large is likely to be much warmer even though the large one will have a greater total fill weight.

Here are the old calculated lofts

50f – 1.1 (sewn through)

40f – 1.95″

30f – 2.6″

20f – 3.25″

10f – 3.9″

0f – 4.55″

-10f – 5.2″

-20f – 5.85″


Here are the new default calculated lofts

50f – 1.1 (sewn through)

40f – 2.24″

30f – 2.99″

20f – 3.74″

10f – 4.49″

0f – 5.23″

-10f – 5.98″

-20f – 6.73″


As noted above, temperature rating is very subjective and at the end of the day if my estimated rating is too high or too low for someone, they can simply ask for whatever amount they need to be warm.