It is one of the most searched questions about phones, and it is easy to see why. A switched-off phone feels like a locked room, and locked rooms are irresistible. The honest answer is deflating in the best possible way: a genuinely powered-off phone is, for practical everyday purposes, dark.
Location works because a phone is actively doing something, computing a GPS fix, chatting to cell towers, scanning for wifi. Cut the power and all of that stops. There is no satellite that can reach down and interrogate a dead device, and no website, ours very much included, that can conjure a location out of silence. When the radio is off, there is nothing to hear.
Where the "sort of" creeps in is the difference between off and appears off. Some modern phones keep a sliver of low-power circuitry alive for features like find-my-device when the battery dies, and sophisticated malware can make a phone fake a shutdown while quietly staying awake. These are real but narrow cases, and they involve the phone not actually being off at all.
There is also the ghost of the past. Before it went dark, the phone left a trail: its last known position, its last tower connection, the breadcrumbs of where it had been. That history can sometimes be reconstructed after the fact by people with legal authority. But that is memory, not live tracking, and it is not something available to a member of the public with a phone number and a hunch.
For how live location works when a phone is on, see our GPS explainer and the tracking overview.
So the thriller where the villain is followed to their lair despite a powered-down phone is, comfortingly, fiction. A phone that is truly off keeps its secrets. And if that fact makes you feel a little less watched in the world, good. That is rather the reassurance this whole cheerful hoax exists to offer.