A thread gage, also known as a screw gage or pitch gage, is used to measure the pitch or lead of a screw thread.

Thread pitch gages are used as a reference tool in determining the pitch of a thread that is on a screw or in a tapped hole. This tool is not used as a precision measuring instrument, rather it allows the user to determine the profile of the given thread and quickly categorize the thread by shape and pitch. This device also saves time, in that it removes the need for the user to measure and calculate the pitch of the threaded item.