It’s probably of no use when you are not using your android smartphone, WiFi sys background apps and uses data. So ultimately you can improve smartphone’s battery life will be increased. Here is how you can set up Disable WiFi Automatically during your screen is off and you are not using your device.

Here are few steps to be followed to setup automatic turn off your smartphone’s WiFi.
1. Go to setting menu from your smartphone and then tap on WiFi option.
2.Now you will be in WiFi menu, there tap on options button to show advanced menus. Tap on Advanced menu.
3. You are now on advanced WiFi setting menu. There you will see keep WiFi on during sleep. Tap on the option for setup.
4.There will be now three options, say always, when plugged in and never( increases data usage). Select Never (increase data usage) from that three option.
Related : Use Android as Wireless Hotspot
When you select always, it will keep your WiFi on during your device’s screen is off. If you choose when plugged in, it will keep WiFi on when your device screen is on or device is in charging. Otherwise, WiFi will be kept off automatically. If you select Never( increase data usage) option, whenever your screen off, it will automatically switch off your device’s WiFi.