MacBook shuts down at 20% or 10%: why, and what to do
Why a MacBook turns off while the battery still shows charge, how a worn battery and heavy load cause it, and when it means replacement.
Why does my MacBook shut down with battery left?
Under heavy load a worn battery's voltage drops sharply, below what the Mac needs, even though the estimate still shows charge. The Mac turns off to protect itself.
How do I check if the battery is the cause?
Check Maximum Capacity and Condition: how to check battery health. Low capacity or Service Recommended with early shutdowns points to the battery.
What can I do until it is replaced?
Plug in earlier, lower brightness and avoid heavy work on low battery. A full charge cycle can make the estimate more realistic: calibration.
Common questions
Why does my MacBook die at 30 percent?
A worn battery's voltage collapses under load before the estimate reaches zero.
Is it safe to keep using a MacBook that shuts down early?
Yes, but save often and replace the battery; sudden shutdowns can lose unsaved work.