Check Battery Status Online

Chrome, Edge, Opera and other Chromium-based browsers. Firefox removed support in version 52 and Safari never shipped it — those browsers will see the unsupported notice instead.

No — browsers only expose level, charging state and time estimates, not the deep battery health figures (cycle count, design capacity, full-charge capacity) that the OS keeps to itself. For those you need OS-level tools: on Windows run "powercfg /batteryreport", on macOS check System Information → Power, on iPhone go to Settings → Battery → Battery Health, on Android dial *#*#4636#*#* or use AccuBattery.

A typical Li-ion battery is rated for ~500 full charge cycles to 80% capacity (phones) or ~1000 cycles (modern laptops). Most manufacturers consider the battery worn out once it drops below 80% of its original design capacity — that is also the threshold for warranty replacement on iPhone, MacBook and Samsung devices.

The OS reports infinity when it has no reliable estimate — usually right after plugging in (still measuring), at full charge, or when the discharge rate is too small to project a finish time. Wait a minute or two; once a stable rate emerges the number stabilises.

No — Safari does not expose battery data on any Apple platform. On iPhone, the equivalent info lives in Settings → Battery (24-hour graph) and Settings → Battery → Battery Health (maximum capacity vs new, peak performance capability).

Calculated from real level changes during your session — the longer you leave it open, the more accurate the projection. Some browsers round the level to the nearest 5% for privacy, which makes short-session estimates jumpy. Leave the tab open for at least 10 minutes for a stable %/hr reading.