Don't even try to measure your insole, you'll never get it right. Just look at the measurements on any of your sneakers in CM or CHN. Then take that information and find the corresponding US size in the size guide. For example, the insole length of 25 CM corresponds to US 7 in Vans. You may get a different US size with a different brand due to slightly different measuring.
Stance is producing extremely comfortable and high-quality socks that are now being sold in more than 40 countries around the world. It is not a coincidence that the Face of this company are usually celebrities like Rihanna or Big Sean or sport legends like Allen Iverson, Andre Drummond, etc. Stance produces stylish socks for everybody who dare to be different. Have you ever had socks that are actually a piece of art?