Approximately 2.5 inches long. Plenty of room for an old photo to fit! I’ve seen some really tiny lockets that fit pics but this is very spacious! When I bought her, she was actually glued shut! I saw the hinge and proceeded to clean her up and eventually she opened! When it’s opened, the top with the jewels also came off like it was interchangeable??? Not sure. But the top I left off unglued until I ask the owner what to do lol.