Approximately 24.5cm on each side. This is a set of 5 Shokado lunch boxes with lids. The lids are unused, but the boxes themselves and the wooden boards have been used several times, so they are used items. There are no noticeable scratches or stains, but please check the photos. I also have various dishes to put inside the Shokado boxes, which I plan to list in the future. Thank you.