How accurate is Find My Friends locations? If someone's location is updating, could the location be wrong or lagging?

It is as accurate as the location information their phone is getting. And that can vary a great deal. GPS signals are subject to interference from buildings, trees, weather. The phone may be getting location information from a WiFi network that is inaccurate. Find My Friends is certainly not accurate enough to be relied on in any life or death situations. Nor should it be used as "evidence" that children or spouses are lying to you.

cali4213 wrote:

Even if their location is updating/refreshing every few minutes. I would think if it refreshed then it would go to their current location if it was lagging.

Could it be be lagging by an hour or 2 while showing me previous transit in real time?

How accurate it is depends on such a large number of factors that anything is possible. If the phone isn't getting a good location signal, it could be showing you old or incomplete data. Again, Find My Friends should probably be labeled "for entertainment purposes only".

I get times when my wife or kids should be able to get a location that the app displays "Location not available" or many times get locations that are not completely accurate. Right now it shows my son is at school so that's good. 😉 Not sure what you're experiencing but I would never use Find My Friends to accuse someone of anything or get them in trouble because the app didn't give accurate information.

There was a story recently in the news where a home in Atlanta keeps popping up on Find my iPhone for people with lost or stolen phones and no one can determine why. They believe that it probably has something to do with cell phone tower triangulation but this couple continues to get people showing up on their door demanding their phone and some arrive with police officers. http://bgr.com/2016/01/22/find-iphone-stolen-lost/

If you need to know exactly where someone is, best bet would be to hire a private investigator.