from: https://markhedleyjones.com/projects/calibration-checkerboard-collection
Calibration Checkerboard Collection
Checkerboards can be used with camera calibration tools such as the camera_calibration package for ROS. You can freely download a wide range of checkerboards, with no watermarks or advertising, in PDF format by clicking any of the links below. Additionally, a javascript based checkerboard generator has been added that allows you to generate custom sizes.
TIP: Make sure to disable any page scaling or automatic page fitting features when printing otherwise the checker dimensions will be incorrect.