Restart iPhone

Simply press and hold down the power and volume buttons, then slide the power option to the right and the device will completely shut down. After it turns off, go ahead and hold down the power button to restart it; if your battery is still draining quickly, move to the next step.

Close Apps

Apps can drain your battery quickly, so uninstall any power-hungry ones that you’re not using. Open your settings menu and navigate to Battery, where you’ll be able to see a breakdown of each app and its usage by the last 24 hours, last 10 days, and in total.

Change Settings

Disable location tracking for any apps that don’t need it or setting them to only use it when you have the application open. Open your settings menu, scroll down to the app that you want to change the settings for, and then tap Location to select between the different usage settings.

Try Low Power

When enabled, Low Power Mode will reduce your iPhone's power consumption by turning off background features like mail fetch, background app refresh, and automatic downloads. Using it is only a temporary fix, though, and shouldn’t be employed all the time.

Reset iPhone

As a last resort option, you can reset your phone completely, but you will lose all the apps that you’ve downloaded and any data. Head to the settings menu, select General, scroll down and tap Transfer or Reset iPhone, choose the Reset option and then Reset All Settings.