Old Nokia and other dumb phones had a great feature: the alarm would sound even when the phone was turned off. This meant you could go to bed knowing your phone wasn’t going to make a sound until it was time for the alarm to wake you. But what about modern iPhones? Will their alarms go off if Do Not Disturb is enabled?

Will the Alarm Go Off If My iPhone Is Off?

No. The alarm won’t sound if your iPhone is switched off. If you want an alarm to go off, your iPhone must remain on. It can be in sleep mode (with the screen off), on Silent, and even have Do Not Disturb turned on and the alarm will still sound when it’s meant to.

Will the Alarm Go Off If My iPhone Runs Out of Battery?

No. If your iPhone runs out of battery during the night, the alarm you’ve set for the morning won’t sound.

iPhones are pretty good at holding their charge if you’re not using them, especially when you turn on Low Power Mode. So, you don’t need to worry too much if you have around 20% battery left. On the other hand, if you have 5% or so battery left and are bedding down for an eight hour sleep, there’s a very good chance it will run out of juice during the night.

Do Alarms Go Off If My iPhone is On Silent?

Yes, your alarms will still work so long as your iPhone is on, even if it is on silent.

Will My Alarm Work if I Enable Do Not Disturb (or other Focus Modes)?

Yes. Alarms can sound through Do Not Disturb and every other Focus mode on iPhones. Focus modes only change the behavior of notifications from apps, not alarms.

Will the Alarm Go Off If My iPhone’s Screen Is Off?

Yes, the screen going black is just a normal power saving feature of your iPhone. As long as when you touch the home button, it lights up again, the alarm will sound when it’s meant to.

Will a Timer Go Off Even If An Alarm Won’t?

Timers, calendar appointments, and reminders all work the same way as an alarm. If you set a timer and then turn your iPhone off, the timer will not sound. Instead, when you turn your iPhone on again, the timer will sound straight away—presumably to remind you that you missed a timer.

If, for some reason, your iPhone is so low on battery that it won’t make it through the night—and you can’t charge it—but you desperately need an alarm to wake you in the morning, you will need to get creative. Dig out an old alarm clock, steal a charger, or beg a trusted friend (or the hotel reception desk) to ring you in the morning. You won’t be able to rely on your iPhone.