When measuring the diameter of a bolt? Measure on the outside of the thread measure on the inside of the thread

When measuring the diameter of a bolt, it is important to measure on the outside of the thread. This is because the bolt is designed to have a consistent diameter along its length, and the threads are simply a means of allowing it to be tightened or loosened. Measuring on the inside of the thread would not provide an accurate measurement of the bolt's diameter.