On it's own, about the same as most bluetooth...about 30 feet. However if you are on wifi, it learns the same wifi connections as the phone and can function on it's own. When you say hello to Apple Watch, you say goodbye to Fitbit. The apple watch will not natively share data with the Fitbit app, and even if you buy a third party app that will import the steps, Fitbit still will not count these steps towards achievements from any non-fitbit device.