How to Find a Lost Nintendo Switch or Joy-Con

What you’re dealing with

Controllers advertise clearly as Joy-Con (L) or Joy-Con (R), which means a scan tells you not just that one is nearby but which one.

Broadcasts as	Joy-Con (L), Joy-Con (R), Pro Controller
Typical battery	About 20 hours on a Joy-Con, 40 on a Pro Controller
Findable by scan	Yes, while powered on
Search window	Days to weeks

Once the battery is gone: Controllers sleep rather than shut down, and a sleeping controller still advertises for a long time.

Detached during play and swallowed by the seat.

Carried to a bedroom and dropped.

In a house with children, the default destination for everything.

Check the last-seen map firstBefore you search a room, find out which building. A pin saves you from searching the right way in the wrong place.
Scan from the middle of the roomNote everything that appears, then select the device you want so the rest of the list drops away.
Walk and watch the signalSweep in a straight line, give each position a few seconds, and turn 90 degrees when the reading stops rising.
Search inside things, not across themA strong signal with nothing visible means it is underneath or inside something. Fabric and metal block Bluetooth badly.

Scan for Joy-Con and check the L or R in the name so you know which one you are chasing.
A sleeping controller still broadcasts, so it is worth scanning even if the console has been off for weeks.

The same method applies to these, with different battery windows and different hiding places.

Usually yes. Sleep is not the same as off, and a sleeping controller continues to advertise over Bluetooth Low Energy.