Battery test

See battery level and charging state, and leave the page open to measure how fast it drains.

  • Test data stays on your device
  • Runs in your browser
  • Free, no sign-up

About this test

The battery test reads the Battery Status API to show level, charging state and the time-to-full or time-remaining estimates. Leave it open while you work to chart the level and calculate the drain rate in percent per hour, a simple way to compare power settings or spot a battery that is wearing out.

How to use this test

  1. Unplug the charger to measure drain, or plug in to measure charging.
  2. Leave the tab open for at least 15 minutes.
  3. Read the rate. More than 20 %/h at light use suggests heavy background load or a worn battery.

Frequently asked questions

Why does my browser say battery information is unsupported?

Firefox and Safari removed the Battery API for privacy. Use Chrome, Edge or Opera.

Can this measure battery health?

Not directly. Windows users can run powercfg /batteryreport; macOS shows battery condition in System Settings.