How to compare insulating insoles?

If the thicker ones have greater insulation they may not be warmer if they cramp your feet in your boots. If you already have both then I think some experimentation with fit is in order first. My Sorbothane insoles are thicker and warmer than my Superfeet ones but meant I could only wear one pair of socks in my mountain boots and also the Superfeet were less sweaty, probably due to the holes punched in them

I wanted to test a few insoles some years ago. What I did was simply boil a pot of water, sandwich a kitchen thermometer between the insoles, put the hot pot on the insoles with 20 pounds added on the pot and take readings for 10 minutes to see which one had the most favorable heat transfer curve. That’s not ideal as the temperature delta was quite larger than real world usage, and absolute temperatures not quite realistic, but I was satisfied it was sufficient to rank insoles relative to one another.

That sounds like a reasonable idea – I think I will try that!

Also consider if the insoles have open cell foam or other water-retaining materials. Waterlogged insoles take forever to dry and likely are less warm that non-permeable insoles. For example, the Dr. Scholls Sport Gel insoles have a foam material adjacent to the foot that retains water a long time, even though the gel portion of the insoles retains no water and dries instantly.

Here is the way I did it when I was trying to chose in early 2018 when my feet were getting cold in the mountains.

https://www.dropbox.com/s/5q3en18rqthp8me

I never wrote this up, so you can just enjoy the images.  However, as a simple guide–colder temperatures win.  I have been using the Sole Insulated Reponse as a result of the test.