Big and tall office chairs consisting of heavy duty office seating is a true specialty category. The big and tall chairs in this heavy duty office furniture section are rated for at least 300 lbs. We also have a 24/7 category 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). Most office chairs carry weight limits of 250 lbs. and their warranties cover a 40 hours per week. If you do not see a weight specification listed on a product it's pretty safe to assume that the limit is 250 although some are only rated for 200 lb. users. 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.