Your MacBook battery is draining fast

Updated 23 August 2026 · every figure below comes from our own measurements on two Apple silicon Macs, and links to the page where that measurement is written out. Who measures this.

Four different problems share this one symptom, and only one of them is the battery. Each has a tell you can check in a minute, so start by working out which case you are in rather than applying advice for a different one.

Tell them apart first

What you notice	Likely case	Where to go
Drain while you work, fan audible, one app busy	A heavy app	what apps actually cost
Drain while you work, nothing obviously running	The machine's floor	watts by workload
Charge gone by morning, lid was shut	Overnight wake-ups	what a normal night costs
Same work as last year, half the runtime	A worn pack	check the real health number

Case one: one app is most of the bill

This is the case people assume first, and it is real, but it is narrower than the folklore. Measured across two Macs, the spread between apps is about four hundredfold: Slack sat at 0.01 W while Xcode ran a typical 3.7 W with a busiest window of 48.5 W. Quitting the wrong one buys you nothing you can notice.

The tell is simple: if the fan is audible or the machine is warm with the screen dim, something is working. If the machine is cool and quiet, no app is the culprit and quitting things will not help.

Case two: nothing is running, and that is the answer

On a quiet Mac most of the power goes to the screen and to simply being awake. On the second of the two machines we measure, that floor took about two thirds of the energy in a window, leaving apps a sliver. In two sessions out of five there, so little belonged to apps that the honest answer was "there is nothing here to close".

You cannot subtract an app's watts from the machine's and call the difference savings, because the screen and being awake do not go away when the app does. On the quiet Mac that subtraction broke in 117 of 157 measured windows.

What actually moves this number is screen brightness, and after that whether the machine is allowed to idle at all.

Case three: it happens with the lid shut

Sleep is not free, and there is a normal rate. Roughly a third of a percentage point per hour while genuinely asleep, which puts a nine hour night near 3%, and 3 to 5% once the scheduled wake-ups are counted. Above about 2% per hour it is not sleep any more, and something is holding the machine awake.

The wake-ups themselves have names in the power log, and most are ordinary maintenance. What we cannot honestly tell you is what any single one cost: macOS reports charge in whole percentage points, and a thirty second wake does not move a whole point. The night study has the counting trap most guides fall into, including the one that made us withdraw our own first ranking.

Case four: the pack is worn

This is the only case where the battery is the problem, and it is the easiest to check: your Mac stores two capacity figures and shows one of them, rounded. The health checker prints both in one command.

Worth knowing before you read the number: health and runtime are related but not the same thing. A pack reading 96% can still run four hours if the machine is doing more than it used to, which is its own case.

Questions people ask

Does quitting apps actually save battery?

Sometimes, and the amount is measurable rather than a matter of opinion. When one app is most of the use, quitting it is worth real minutes. When the floor is most of the use, it is worth almost nothing. We measured both cases.

Should I close browser tabs?

Tabs matter less than the browser being busy. Chrome held a median of 16 processes on one Mac and 19 on the other, peaking at 40, and a tab you close takes its process with it. The measured figure is on the Chrome page.

Is Low Power Mode the answer?

It stretches the charge you have by slowing things down, which is a different job from finding what is spending it. If you want the cause named rather than the symptom dimmed, that is what this site is about.

My Mac drains while plugged in

That usually means the adapter cannot supply what the machine is drawing, so the battery makes up the difference. It is common with lower wattage chargers under heavy load, and it is not a fault of the battery.