Vernier calipers commonly used in industry provide a precision to 0.01 mm (10 micrometres), or one thousandth of an inch. They are available in sizes that can the number of lines between two numbers on your Vernier scale. Use this to determine how much distance each of the smallest lines represents.Before measuring anything, close the jaws and faces to zero out the reading so that you get a precise measurement. If you don’t do this, you won’t start with your scales lined up at zero when you take your measurement, and you will have to correct for the zero error.