Rain gauges come in all different sizes, and in different price ranges.
Some are meant for home and garden use, and others are used for official measurements for the National Weather Service. The official rain gauge in the U.S. is an 8-inch diameter metal tube, and is used by the National Weather Service observing sites, and thousands of volunteer cooperative observers around the nation. There are many different kinds of rain gauges also. Some actually weigh the rain, and record the amounts on a chart. Inexpensive plastic rain gauges work very well for a homeowner or gardener.