Why your Mac's battery time remaining keeps changing
The time remaining estimate follows what the Mac is doing this minute. On ours it read 1h 0m, 1h 24m and 1h 38m within an hour at similar charge. How to read it.
How does macOS estimate time remaining?
It divides the charge left by the power the Mac is drawing now, smoothed over the last few minutes. Change what you are doing and the draw changes, so the estimate changes with it.
| Moment on our Mac | Charge | Estimate |
|---|---|---|
| Recording the screen while moving windows | 30% | 1h 0m |
| Lighter work a little later | 27% | 1h 24m |
| Idle in between | 28% | 1h 38m |
pmset -g batt | 21% | 1:21 |
How do I see time remaining?
pmset -g battPrints the source, the percentage and the estimate. Battery settings show it under the chart, and Free Mac's System tab shows it beside the draw.
See it live
Free Mac's System tab shows what the Mac is drawing from the adapter and the battery, and ranks what is draining it by energy impact, every second. See also what energy impact means.
Related: use caffeinate and pmset: change Mac sleep settings in Terminal.
Common questions
Why does my Mac battery time remaining keep changing?
It is based on the power draw right now, which changes with what you are doing.
How do I see battery time remaining on a Mac?
Run pmset -g batt in Terminal, or look under the chart in Battery settings.
Is the Mac battery estimate accurate?
Only for the current workload. Ours ranged from 1h 0m to 1h 38m within an hour at similar charge.