Not thick enough. The chair will get stuck in indentations that are created If you have to sit in a single position for any length of time. Even shifting the mat doesn't work; creates more indentations. It does grip low pile carpet though.
I had ordered a different mat that over time cracked under my office chair wheels. I realized that I hadn't measured the depth of my carpet correctly (didn't include the pad) and ordered this mat to replace. This one is thicker and more solid and feels like it will last a long time. It arrived slightly bent but I flattened it with some heavy boxes in about a day.