So you need your iPhone to last the entire day, but you don't have access to a charger. What do you do?
First, you should always make sure to follow the tried-and-true tricks such as turning your iPhone's brightness down and turning off Wi-Fi and Bluetooth. It's nothing new, but it definitely matters.
Next, you should navigate to Settings > General > Usage > Battery Usage to take a look at what apps are using up your battery life in the background, and close any you can down for the time being.
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Just tap the crescent moon to turn on and off "Do Not Disturb" mode.
These tricks are great, but when you need to squeeze every last minute from you iPhone, one simple setting will dramatically reduce the number of times your screen turns on while in your pocket, which can add up throughout the day.
It's called "Do Not Disturb" mode, and it's easily accessible by swiping up from the bottom of your iPhone's lock screen.
Just swipe up and tap the tiny crescent moon icon to turn it on.
Do Not Disturb is a great tool for making your battery last, but while enabled, you won't receive a vibrating or audio notification if someone calls or messages you, so you'll need to manually check.
But if you know you'll need to save your iPhone's battery for later, "Do Not Disturb" mode can give some extra legs to your battery life so you're not left staring at a blank screen.