DIY Frequently Asked Questions / Why does the hook on the end of my tape measure move slightly? Doesn’t that affect the final reading? Do I need to get a new one for my toolkit?
It is designed to slide the same amount as the thickness of the end of the hook. That way it can accurately measure distances when the tape is hooked to the end of an object (such as the end of a board) or when measuring between objects (such as the width of a door jamb). If it were fixed, one of these two measurements would be off by the thickness of the hook.