Logitech battery questions

Back to the battery checker

Which Logitech devices work

Anything that speaks HID++ over a Unifying receiver, a Bolt receiver, a Lightspeed dongle, Bluetooth or a USB cable. That covers most Logitech mice and keyboards made in the last decade, including:

How do I check the battery level on an MX Master?

Plug in the Unifying or Bolt receiver, or pair over Bluetooth, then open the battery checker, click Add device and choose it from the browser's list. The MX Master battery level appears within a second or two, along with anything else paired to the same receiver.

Why does my Logitech mouse show no battery level while charging?

Many Logitech mice, the MX Master 3 included, stop reporting a battery level the moment they start charging, and report one again once charging finishes or the cable comes out. That is the mouse's firmware rather than a fault in the page: the reply carries a zero where the level should be. Unplug the mouse for a second to get a reading straight away.

Why is the percentage approximate?

Plenty of Logitech devices have no fuel gauge. Instead of a true percentage they report a handful of fixed levels, so an MX Master 3 only ever says 100, 50, 20 or 5. A tilde marks a reading that came from one of those buckets rather than a real measurement. Devices that do have a gauge show an exact number with no tilde.

Do I need Logi Options+?

No. This is an alternative to opening Logi Options+ just to read a battery percentage. It does not change any device settings, and it works alongside Logitech's software without interfering with it.

Which browsers work?

Chrome, Edge, Opera, Arc and other Chromium browsers, on Windows, macOS, Linux and ChromeOS. Safari and Firefox do not implement WebHID, so the page cannot read anything there. The page also has to be served over HTTPS, because WebHID refuses to run outside a secure context.

Is my data sent anywhere?

No. The page has no analytics, no cookies and no server calls. Everything happens between the browser and the device, and the only thing stored is the last battery level each device reported, kept in your browser so a reload during charging still has something to show.