How thin can a travel yoga mat be before it becomes uncomfortable?

Most travel mats fall between 1.5mm and 3mm. Reviewers consistently note that ultra-thin (1.5mm) mats like the Manduka eKO SuperLite fold and pack the smallest but transmit hard floors directly to the knees, so they're best used over carpet, a studio mat, or with a folded towel for kneeling poses. If you want a mat that feels closer to a studio mat, look in the 2mm to 2.5mm range.