why is this so gosh-darned complicated?!

PINHOLE PHOTOGRAPHY AND CAMERA DESIGN CALCULATORS

Pinhole Camera Design Calculator

Focal length mmin Optimal diameter mmin Pinhole diameter mmin Optimal Focal Length mmin F Stop Image Diameter mmin Film Dimension mmin AngleOfView degrees Film Speed ISO/ASA Sunny Day Exposure

calculations for how to convert the size of your pinhole from millimeters to inches? how bleeding small are the tools we need to measure these effing holes? sorry, just going a little crazy trying to get a decent photo. don't mind me!