Quick answer
The most common causes are too many open browser tabs, background apps, or simply a battery that's naturally worn down after years of use — all checkable in your settings.
macOS has built-in tools that show exactly what’s consuming battery — the first step is always to see what’s actually happening, not guess.
How to diagnose it
Under System Settings → Battery, you can see which apps are using the most energy. It’s often browser tabs playing video or apps that keep running in the background without you noticing.
When it’s battery wear
The same settings section shows “Maximum Capacity” — if it has dropped below 80%, that’s normal wear after years of use, and a battery replacement will fix it.
- Check which apps are consuming energy
- Close unnecessary browser tabs
- Check Maximum Battery Capacity