MacBook battery draining fast: daytime drain vs overnight drain, and how to find the cause

First, which kind of drain do you have?

Before changing any settings, work out when the battery is going. The fix for a Mac that drains while you work is completely different from the fix for a Mac that drains while it is shut in a bag, and most guides mix the two together.

Daytime drain looks like this: you unplug at 100 percent, work for two or three hours, and you are already under 40 percent. The Mac is probably warm and the fan may be audible. Something is using the processor hard the whole time. On an Apple silicon MacBook Air or Pro that should be good for a full working day, this is almost always one app, one browser tab, or one video call doing far more than it needs to.

Overnight drain looks like this: you close the lid at 80 percent and open it the next morning at 40 percent or lower, and the Mac was not plugged in. A properly sleeping MacBook loses very little charge. Apple's own support note says a Mac in sleep "will occasionally wake from sleep for short periods of time to maintain network registrations", and those short wakes cost almost nothing. Losing a quarter or half of the battery means the Mac was awake for hours while the lid was shut.

Open System Settings, Battery. The graph at the top shows charge level over the last 24 hours. A sleeping Mac draws a nearly flat line. A Mac that was woken repeatedly draws a line that steps down overnight, and a Mac that was held awake for a long stretch shows a steady downward slope. That one graph tells you which section of this page to read.

Why the battery drains fast while you are using it

The honest answer is that it is usually one thing, and you can find it in about a minute. Open Activity Monitor (it is in Applications, Utilities, or press ⌘ Space and type its name), click the Energy tab, and click the 12 hr Power column header so the biggest number is at the top.

The Energy Impact column is a live score of how much power each app is using right now. The 12 hr Power column is the average over the last 12 hours, which is the one you want, because a tab that spiked for ten seconds does not matter and a tab that has averaged high all morning does. The names at the top of that sorted list are your answer.

What tends to be up there:

• A browser tab running flat out. A page with an auto-playing video, a heavy web app, or a tab with a broken script can sit at 100 percent of one core for hours. In Chrome and Safari the culprit shows as a helper process ("Google Chrome Helper (Renderer)" or "Safari Web Content"). Close tabs you are not using. Safari's own Activity window and Chrome's Task Manager (Window, Task Manager) name the exact tab.
• Video calls. Zoom, Teams, Meet and FaceTime are among the heaviest things a laptop does: camera, microphone, encoding your video, decoding everyone else's, and often screen sharing on top. An hour-long call can use more battery than three hours of writing. This is normal, not a fault. Plug in for calls when you can.
• Screen brightness and keyboard backlight. The display is the single biggest fixed cost on any laptop. Brightness at 100 percent versus 50 percent is a noticeable chunk of battery life. Turn on auto-brightness (System Settings, Displays, Automatically adjust brightness) and let it do the work.
• An external display. Driving a second screen, especially a 4K one, keeps the graphics hardware busy and WindowServer working harder. Expect shorter battery life whenever one is connected without power.
• Background indexing after an update or a big import. Spotlight and Photos analysis run for a while after a macOS update or when you add thousands of files. They settle on their own; see why a Mac is slow after an update.

Two things to not bother with: closing every app "just in case" (an idle app in the Dock costs essentially nothing) and installing a battery optimizer. Low Power Mode (System Settings, Battery) is a real and safe setting that caps performance to extend battery, and is worth turning on for a long day away from a plug.

Why the battery drains overnight with the lid closed

When you close the lid, macOS puts the Mac to sleep. Sleep is not off: the Mac can be woken, briefly or for a long time, by several things, and each wake costs battery. The pattern of a bad night is either dozens of short wakes (a few percent each, adding up) or one long stretch where something held the Mac awake (the expensive case). This is a widget that plays back a typical night from the power log so you can see the shape of each.

The long stretch is the one to chase. Fifty short wakes for network keepalives cost less than a single two-hour stretch where a sync job or a stuck app kept the Mac awake.

What wakes a sleeping MacBook

These are the usual suspects, roughly in order of how often they turn out to be the cause.

• A Bluetooth mouse, keyboard or trackpad. By default a paired Bluetooth device can wake the Mac. A mouse in the same bag, nudged every time the bag moves, wakes it over and over. The setting lives in System Settings, Bluetooth, Advanced (on older versions) or under the device's options; turn off "Allow Bluetooth devices to wake this computer" if you carry the Mac with a mouse. The bluetoothd process is just the messenger here, not the cause.
• Wake for network access. With this on, the Mac wakes so other devices can reach it (file sharing, screen sharing, Find My). It is on by default when plugged in and off on battery on most MacBooks, but it is worth checking in System Settings, Battery, Options. One MacRumors user with a sudden jump from 1 to 3 percent overnight to about 20 percent reported that turning it off pulled it back to normal.
• A dock or dongle left connected. Anything plugged into a USB-C or Thunderbolt port can keep the port powered and can wake the Mac. If the Mac sleeps in a bag with a dongle attached, unplug it.
• Find My and location. A MacBook that is set up in Find My wakes occasionally to report where it is. This is a small, steady cost, and a feature most people want. It is not what drains 40 percent in a night.
• A sync or backup job. iCloud Drive (bird), Dropbox, Google Drive, OneDrive, and Time Machine (backupd) all hold a wake assertion while they work. If you close the lid in the middle of uploading a large folder, the job can keep the Mac awake until it finishes. The AirDrop and Handoff helper sharingd and the push notification service also wake briefly.
• An app with "Preventing Sleep" set to Yes. In Activity Monitor's Energy tab there is a column called Preventing Sleep. Any app showing Yes is telling macOS not to sleep. Media players, download managers, Terminal windows with a running job, and some meeting apps do this, and if they are still doing it when you close the lid, the Mac does not sleep. Quit that app before closing the lid.
• Notifications and Power Nap style work. Modern Macs do small background tasks during sleep (mail fetch, software update checks, iCloud). These are short and cheap, and macOS throttles them hard on battery. They are not the problem unless something above is keeping the Mac from going back to sleep afterwards.

The sleep and wake decisions are made by powerd, which logs every wake with its reason. That log is what the timeline above is built from, and it is the same information the Battery settings graph summarizes.

What a bad night looks like against a good one

What to do, in order

1. Check the Battery graph

   Open System Settings, Battery. Look at the 24 hour graph. A steady slope while you were working means daytime drain (steps 2 to 4). Steps or a slope during the night means wake drain (steps 5 to 8).

2. Sort the Energy tab by 12 hr Power

   Open Activity Monitor, click Energy, click the 12 hr Power header. Whatever is at the top has been using the most battery today.

3. Quit or close the top item

   If it is a browser helper, close tabs until the number drops, or quit and reopen the browser. If it is an app you are not using, quit it with ⌘Q. Give the Energy numbers a minute to settle.

4. Lower the fixed costs

   Turn on auto-brightness, turn off the keyboard backlight when you do not need it, and turn on Low Power Mode in System Settings, Battery for long days away from power.

5. Look for Preventing Sleep

   In the Energy tab, find the Preventing Sleep column (right-click a header to show it if hidden). Quit any app showing Yes before you close the lid.

6. Turn off Bluetooth wake if you carry a mouse

   Turn off the option that lets Bluetooth devices wake the Mac, or simply switch the mouse off before it goes in the bag.

7. Check Wake for network access

   System Settings, Battery, Options. Set Wake for network access to Only on Power Adapter, or Never if you never need to reach this Mac remotely.

8. Finish syncs before closing the lid

   If iCloud Drive, Dropbox or Time Machine is mid-transfer, leave the lid open or plug in until it finishes, then close it. Unplug any dongle or dock.

When it is actually the battery, not the software

If the Battery graph is flat overnight, the Energy tab shows nothing unusual, and the Mac still does not last, check the battery itself. System Settings, Battery, Battery Health shows Maximum Capacity and a condition line. Apple designs current MacBook batteries to retain 80 percent of their original capacity at 1,000 complete charge cycles, and the Battery Health screen will say Service Recommended when the battery is past its best. A battery at 75 percent capacity simply holds three quarters of what it held new, and no setting fixes that.

The other case where the fault is not software: a sudden change after a macOS update, with nothing new in the Energy tab, that goes away a week later. Those are usually indexing and analysis jobs finishing, as covered on the slow-after-update page, and are worth waiting out before you change anything.

Finally, a note on cleaner and "battery booster" apps. They cannot change how much power the display or the processor uses. The two things that actually help are quitting what is busy and stopping what wakes the Mac, and both are built into macOS. If you want the long view rather than a single Activity Monitor snapshot, Safe to Quit tracks each process over hours and flags the ones that stay busy or hold the Mac awake, which is the same question this page is answering by hand.

Related: background items that start at login are a frequent source of small, constant drain, and closing the lid while something is running explains exactly what sleeps and what does not.