To measure 1 inch of water, place a can or several cans across the yard while watering your lawn. The time it takes for the can to accumulate 1 inch of water is the amount of watering time your lawn needs.
A sprinkler timer saves you the headache of turning irrigation systems off and on. You can set the timers to water your yard or garden in the early morning hours, or several times throughout the day. The most popular timers are digital, and can be quite complicated. One example, the Rachio Smart Wifi Sprinkler Controller allows you to control your sprinkler system via your smart phone or computer. More traditional mechanical sprinkler controls are still used, but less often than the digital timers.