Approximately 24.5 to 25 cm square. Please allow for some margin of error. Although unused, it has been stored by a private individual, so it may not be in perfect condition. Please refrain from purchasing if you are concerned. Instant purchase is welcome. If you have any questions, please feel free to ask before purchasing. For a smooth transaction, if you choose to pay at a convenience store ATM, please let me know your expected payment date. Thank you.