How long will my battery last?

Draintest measures the real battery life of your phone, tablet or laptop right in the browser. Start a test, let the device run flat, and look up the result later with your test ID.

Your test ID: #assigning …

> Write this number down! The device will run flat – the ID is how you find your result later.

Battery: …

## Choose test mode


## Look up a result

## Recent tests

IDDeviceModeRuntime0→100 % (estimated)Status
#7 Windows · Chrome 157 Fullscreen video 0:00:19 – stopped
#5 Windows · Chrome 157 Fullscreen video 0:00:18 – last signal
#3 Windows · Chrome 157 CPU full load 0:00:18 – stopped
#2 Windows · Chrome 157 Background 0:01:49 – stopped

## How the battery test works

  1. Open this page on the device you want to test and write down the test ID.
  2. Charge the battery as full as possible, then unplug the charger.
  3. Pick a test mode and start. Every 30 seconds a sample (time + battery level) is stored.
  4. Let the device run flat. The last sample before it shuts down is your real battery life.
  5. Later, enter the ID here and view the result – including a discharge curve and an estimate.

You don't have to wait until 0 %: once the level has dropped a few percent, Draintest calculates how long a full charge lasts under that load.

## FAQ

How long will my battery last?

That depends on battery health, screen brightness and load. Draintest measures it: start a test and after a few percent of discharge you get an estimate of the runtime on a full charge.

How do I know my battery is getting weak?

Compare the measured runtime with the manufacturer's figures or with tests of the same model. If it is far below (e.g. under 70 %), the battery has lost noticeable capacity.

Does the test work on iPhone?

Yes, the runtime is measured. Safari does not expose the battery level to websites, so there is no estimate on iPhone – only the actual time until the device shuts down.

Which test mode should I use?

Background = everyday use, video = streaming/display, CPU full load = worst case (e.g. gaming). For a fair comparison between devices, use the video test at maximum brightness.

Is any data stored?

Only test ID, time, battery level, device type and the optional device name. No cookies, no account. Results are public.