How to measure head circumference for welding cap? Hold the end of the cloth tape measure to the middle of your forehead. If you are using a standard metallic tape measure, use a piece of string. Wrap the tape or string around your head until you return to the starting point. It should be above your ears, resting at the point you would like your hat to rest.
Make sure the tape measure or string is snug around your head, but not too tight. It should be comfortable and just fitted enough to stay put. Write down your measurement in inches. If you are using string, measure the string against your tape measure. Use the size chart above to determine which size will be your best fit. If you are between sizes, choose the larger size.