How to set a battery alarm on your Apple Watch

The short version

There is no battery alarm setting in watchOS. The system warns at 20% and again at 10%, both levels fixed, and the Shortcuts app has no trigger for the watch's battery level — so there's nothing to automate, either. (We've gone through every battery setting watchOS does have separately, if you want the full inventory.)

That leaves three real ways to get something that behaves like an alarm: a repeating alarm at a fixed time, the built-in charge-before-bedtime reminder, and an app that alerts at a battery level you choose. They're not equivalent — the first two watch the clock. Only the last one watches the battery.

Option 1: a repeating alarm at a fixed time

The no-app answer is to make charging an appointment. Set a daily alarm or a repeating Reminders entry — charge the watch, 5 pm, every day — and build the habit around it.

This works better than it sounds, because a watch charged at the same hour every day rarely surprises you. But the alarm is blind. It fires at 70% just as happily as at 25%, so either you start ignoring it on the good days — and then it isn't an alarm anymore — or you charge more often than the battery needs. And on the one day that's different — a long workout, travel, a charge you forgot — the fixed time is exactly wrong.

Option 2: the built-in charge reminder before bedtime

watchOS does have one genuine charge reminder, and it's tied to Sleep. With a sleep schedule set up in the Health app and Charging Reminders switched on (Watch app → Sleep), the watch nudges you before bedtime if the battery looks too low for a night of sleep tracking.

It's worth turning on — it's free, and it guards against the worst case, a watch that dies mid-night and takes your sleep data and morning alarm with it. Its limits are just as real: it only covers the night, so nothing helps you at two in the afternoon, and it fires close to bedtime — often when you're already in bed and the charger might as well be in another room entirely.

Option 3: an alarm that watches the level

The thing people are actually asking for — tell me when the battery reaches a level I choose — only exists as a third-party app. That's the whole of what vaka does: you pick a level between 25 and 90%, and the watch taps your wrist when the battery passes it on the way down.

The details that make it behave like a proper alarm rather than a nag:

• The watch monitors itself.

  Everything runs on the watch — your iPhone can be at home, in a bag, or switched off. The tap arrives anyway.

• One tap per discharge.

  It fires once when the level crosses your line, never while charging, and re-arms itself the next time the watch comes off the charger.

• Snoozable from the wrist.

  Busy when it taps? "Remind me later" or "remind me at a lower level", straight from the notification.

• No account, nothing phoning home.

  There's no networking code in the app at all. It's a one-time purchase, not a subscription.

One honest caveat: watchOS decides when background apps get to run, so the alarm can land a few percent past your line — 47% instead of 50, say. That's a scheduling quirk of the platform, not a fault, and it's why picking a level with some margin matters more than picking a precise number.

The three side by side

Same goal — never a dead watch — three different mechanisms:

If you already charge on a fixed rhythm and it never fails you, keep the routine and skip the apps. The level-based alarm is for everyone whose days aren't identical — which, judging by the support threads, is most of us.

Setting it up takes a minute

Whichever route you pick, set it up once and stop thinking about it:

• For the fixed-time route.

  Set a repeating alarm or reminder at the hour you're most reliably near a charger — for most people that's early evening, not bedtime.

• For the bedtime reminder.

  Set a sleep schedule in the Health app on iPhone, then switch on Charging Reminders in the Watch app under Sleep.

• For a level-based alarm.

  Install vaka on the watch and pick your level — 50% is a good default, higher on long workout days. Fast charging does the rest: the top-up the alarm asks for is usually about ten minutes.

Common questions