Check your battery status in the browser
This battery status checker reads the Battery Status API that Chrome, Edge, Opera and Samsung Internet expose to websites and shows the result as a gauge: charge in percent, whether the device is charging or on battery, and the operating system’s estimate of the time to full or empty. It updates live — plug in the charger and the gauge changes colour within a second.
While the tab stays open it also records a reading every minute and on every change, charts the level over time and works out a measured drain rate in percent per hour. That figure is often more honest than the system estimate, which jumps around with screen brightness and background work. The log can be copied as CSV for a bug report or a comparison between two laptops.
Nothing is uploaded. If your browser does not expose battery details — Firefox, Safari and every browser on iPhone and iPad hide them on purpose — the page explains why and where to find the same information in the operating system.
How to use the Battery Status Checker
- Open the page in Chrome, Edge, Opera or Samsung Internet on a laptop, Chromebook or Android phone. The gauge appears immediately.
- Read the headline: level, state (Charging, On battery or Full) and the system’s time-to-full or time-left estimate.
- Leave the tab open. Readings are added every minute and on every change; the chart and the measured drain rate fill in over the next 10–15 minutes.
- Press Read again to force a reading, Copy log to copy all readings as CSV, or Clear log to start afresh.
- If you see “Battery details are not available in this browser”, follow the instructions shown for Windows, macOS, iPhone or Android.
Battery Status Checker features
Live gauge
Level, charging state and system time estimates update on the API’s levelchange and chargingchange events — no polling, no refresh.
Measured drain rate
Percent per hour from the readings since the charger was last connected or removed, with a projected time left at that rate.
Chart and log
A canvas chart of level against time, coloured by charging state, a table of the last 40 readings and a CSV copy of all of them.
Honest unsupported message
Detects Firefox, Safari and iOS and explains that the missing API is a browser privacy decision, not a battery problem, with the OS alternatives.
Works offline
The page needs no network once loaded, so it can run on a flight to show how a laptop really drains.
Which browsers support the Battery Status API
Firefox and WebKit removed the API after a 2015 study showed that the precise level and timing values could identify a visitor across sites for a few minutes. Chromium kept it but rounds the level to about one percent.
| Browser | Battery API | Notes |
|---|---|---|
| Chrome, Edge, Opera, Brave, Vivaldi (desktop and Android) | Yes | Time estimates may read as unknown for a minute after a change |
| Samsung Internet | Yes | Android only |
| Firefox | No | Removed from web content in Firefox 52 (March 2017) over fingerprinting concerns |
| Safari (macOS) | No | Never shipped; WebKit removed its implementation in 2016 |
| Any browser on iPhone or iPad | No | All iOS browsers use WebKit, so the API is absent everywhere on iOS |
System estimate versus measured drain rate
The time to empty under the gauge comes straight from the operating system, which extrapolates from the current draw at that instant. Turn the brightness up or start a video call and it can halve. The measured drain rate takes the first and last reading since the charging state last changed, divides the change in level by the elapsed time and projects the remaining charge at that average. Over 15 minutes or more of typical use it is a better guide to real battery life than any single system estimate.
Much faster drain than usual with nothing heavy running points to a worn battery, a runaway background process or a very bright display. For the capacity of the battery itself (design versus full charge), use powercfg /batteryreport on Windows, System Settings → Battery on macOS, or Battery Health on iPhone — websites cannot see that.
Tips to make a charge last longer
- Lower screen brightness — the display is usually the single largest drain on a laptop or phone.
- Close tabs with video, animation or audio; the browser’s task manager shows pages using CPU in the background.
- Turn on the operating system’s battery saver mode.
- Disconnect unused USB devices and Bluetooth accessories; switch off Wi-Fi when offline.
- Keep lithium-ion batteries between about 20% and 80% for day-to-day use and avoid charging a hot device; capacity falls faster at high temperature and high charge.
- Pair this check with My Browser Info for CPU threads and memory, or the Refresh Rate Test — a 120 Hz screen uses noticeably more power than 60 Hz.
Battery Status Checker FAQ
Why does the battery status checker say details are not available?
Your browser does not expose the Battery Status API. Firefox removed it in 2017, Safari never shipped it, and no browser on iPhone or iPad can offer it. The battery itself is fine — check it through the operating system, or open the page in Chrome or Edge.
Is it safe for a website to read my battery?
The API only reports level, charging state and the two time estimates — never serial numbers, capacity or health. This page keeps the readings in memory and discards them when you close the tab. The concern that led Firefox and Safari to remove it was cross-site tracking, not access to anything sensitive.
Why is time to empty “not reported yet”?
The operating system returns an unknown value (Infinity in the API) until it has watched the discharge for a while, and again for a moment after you plug or unplug the charger. The measured drain rate fills the gap once two readings differ.
Can this check battery health or capacity?
No. Websites cannot read design capacity, cycle count or wear level. Use powercfg /batteryreport on Windows, System Settings → Battery on macOS, Settings → Battery → Battery Health on iPhone, or Settings → Battery on Android.
Does the page work on a desktop PC without a battery?
Chrome reports a desktop as 100% and charging with no time estimates, which is correct for a machine on mains power.
How accurate is the drain rate?
It is an average over the logged period, so it smooths out spikes. Give it 10–15 minutes and a couple of percent of change; Chromium rounds the level to about 1%, so very short measurements are coarse.