Approximately 15x15 cm. It's a short length. It's convenient because I don't have to roll up long sleeves every time I do housework. Because it's a short length, it can also be used by children. The elastic is tied loosely. Please adjust it and use it. (After adjusting the size, please tie it tightly) We will offer a small discount for bulk purchases. This is handmade by an amateur. Please purchase only if you understand the circumstances. We also have other handmade items for sale. Please take a look if you'd like (^.^) We plan to ship using the most affordable method. #ArmCoverForKids #ShortArmCover