too thin. I weigh 215 and the mat is on a carpet. My weight (plus the chair?) creates a very noticeable indent in the mat. When I go to roll back from the desk the wheels of the chair are in craters and you need to really give it a shove to move the chair. I suspect these repeated craters will cause quick wear in the plastic and it will crack sooner than later.
We bought this mat for our home office to use over standard residential carpeting in what was designed to be a bedroom. The mat works great so far and looks like it will hold up to regular use. We bought it for my husband's chair so the combined weight on it is likely to be over 230lbs. It was delivered without a box laid flat outside our front door and everything is fine. We are pleased with our purchase.