How Much Overnight Battery Drain Is Normal?

A phone sitting untouched overnight should lose somewhere in the low single digits to about 10 percent, mostly from notifications and background syncing rather than the battery itself. If yours drops 20, 30, even 50 percent while you slept and nobody touched it, something specific is running in the background, and it is almost always fixable in under five minutes.

Here is the part neither Apple nor Google puts on a single page: they don't publish one "normal" number, because there isn't one. Overnight drain depends on your signal strength, which apps you've allowed to refresh in the background, how many notifications you get between midnight and 7am, and whether Bluetooth or a hotspot got left on by accident. Two identical phones on two different nightstands can lose completely different amounts of charge for reasons that have nothing to do with battery age.

What the battery itself actually does overnight

Strip away every app and setting, and a lithium-ion cell sitting fully idle loses very little charge on its own. Battery University's testing puts pure chemical self-discharge at around 5 percent in the first 24 hours after a full charge, settling to roughly 1 to 2 percent per month after that, with the battery's own protection circuit adding a few percent more per month of overhead. Scaled down to a single night, that is a rounding error, well under half a percent.

So when a phone loses 20 percent overnight, the battery chemistry is not the cause. Something on the device is actively waking the radio, running a background task, or holding a network connection open. That is a completely different problem from battery wear, and it is worth separating the two: a two-year-old iPhone with declining battery health charges to a lower maximum, but it should still hold that lower maximum overnight in the same way a new one holds 100 percent. If you're chasing a max-capacity number instead, that's covered in our year-by-year battery health guide and the piece on iPhone cycle counts, not here.

The real causes, in the order they actually show up

Apple's own support page on rapid battery drain lists the same handful of culprits every time a user's battery usage chart gets checked, and Android's equivalent guidance names nearly the same list:

• Background app refresh and mail fetch. Apps checking for new content on a schedule, especially email clients set to "push" or "fetch every 15 minutes," are the single most common overnight drain source on both platforms.
• Notifications waking the device. Every push notification lights the screen briefly and wakes the radio to receive it. A chatty group thread or a news app with alerts on can add up to real battery over seven or eight hours.
• Weak signal or no coverage. A phone with one bar spends the night repeatedly searching for a stronger connection, which burns far more power than sitting on a strong, stable signal. This is worse in basements, on trains parked overnight, or anywhere at the edge of coverage.
• Location services running in the background. Apps with "Always" location access (rather than "While Using") can poll GPS overnight for reasons that have nothing to do with anything you actually need done while asleep.
• Bluetooth, hotspot, or a stuck sync left on. None of these are heavy on their own, but a hotspot accidentally left broadcasting, or a sync that got stuck retrying, can run all night.

Where to look on each platform

iPhone and Android both give you the actual answer rather than a guess, if you know where to check.

Apple's guidance is specific about what Low Power Mode actually switches off overnight: Mail fetch, Background App Refresh, and Hey Siri, among other things, which is exactly the list above. On the Android side, Google's Adaptive Battery feature is designed to learn which apps you actually use and restrict background activity for the ones you don't, which is why a phone gets better at overnight drain over its first couple of weeks rather than immediately.

If the app-by-app chart shows one thing you don't recognize eating 15 or 20 percent by itself, that is your answer. Force-close it, check its background permissions, or turn off its notifications, and check again tomorrow morning rather than guessing at a fix.

When it's actually the signal, not an app

Apple's own troubleshooting page calls this out directly: a device searching for weak or absent signal burns noticeably more power than one sitting on a strong connection, and the fix is either moving to better coverage or switching to Airplane Mode if you know you'll be somewhere without service overnight (a hotel room with thick walls, a basement bedroom, certain train routes). This one is easy to miss because it looks identical to "my phone is just draining for no reason" until you check the signal bars on your nightstand.

A full day away from an outlet is a different problem than one night on a nightstand. If you're out from morning until midnight with no charger in sight, a powerbank rental network like Brick exists for exactly that gap, not for solving why your phone drops 30 percent while you sleep six feet from a plug.

Frequently asked questions

Is losing 20 percent battery overnight normal?

Not for a phone that's just sitting there. Pure battery self-discharge is under half a percent overnight. Twenty percent points to a specific app, a weak signal spot, or a setting left on, not normal chemistry, and checking your battery usage chart by app will usually show which one within a minute.

Why does my phone still lose battery in Airplane Mode?

The screen, the always-on display if you have one enabled, and any local processing the phone does (indexing, scheduled maintenance tasks) still use a small amount of power even with the radio off. It should still be a very small drop, well under what the same phone loses with a normal signal and notifications running overnight.

Does overnight drain mean my battery is wearing out?

No. Overnight drain is about what's actively running while you sleep. Battery wear is about how much total charge the cell can hold compared to when it was new, which is a completely separate number you check under Battery Health, not by watching the overnight percentage.

Should I turn my phone off completely overnight to save battery?

It will save you the small percentage that background tasks and notifications use, but you lose alarms, calls, and any notifications until you turn it back on. Low Power Mode or Battery Saver gets most of the same benefit without losing functionality, which is why it's the setting Apple and Google both point to first.

Does leaving my phone on the charger overnight cause the drain I'm seeing the next morning?

No, this is a separate and unrelated question. If your phone finishes charging well before you wake up, it isn't drawing meaningful extra power, and overnight-charging habits are about long-term battery health and cycle count, covered in our piece on whether the 80 percent charging limit is worth it, not about how much charge you have at 7am.

What's the single most common fix?

Turning off Background App Refresh for anything except messaging and maps, and switching chatty apps' location access from "Always" to "While Using." Between those two, most reported cases of unexplained overnight drain resolve without needing to reset or replace anything.

Check your battery usage chart tonight rather than guessing at a fix tomorrow. Both platforms will name the actual app or condition responsible, and in most cases the fix is one toggle, not a new battery.