Executive big and tall chairs are rated for at least 300 lbs. and are the top of the line in this category. Some of these chairs are also rated 24/7 which includes heavy duty office chairs that also have an added rating that warranties them for 24/7 use (more than the 40-hour work week). We make special efforts throughout our site to list the weight capacities on each product page. Certain manufacturers, such as Humanscale and Knoll build all of their chairs to accommodate sitters in the 300 pound range and many of their chairs are also 24/7 rated. if you have any questions about their weight or 24/7 rating, please let us know.