How Accurate is the iPhone GPS?

If you've done any traveling, or just needed directions to a nearby restaurant, I'm guessing your iPhone has already saved the day a few times over with it's built-in GPS navigation system.

You can hone in on your current location by tapping the GPS locator button on the lower left of your Google Maps screen.

And you can search for nearby locations, and the iPhone will give you step by step instructions for getting there from your current location.

I've used the iPhone's GPS in several major cities across the US, in Zurich, Switzerland, and in a couple weeks I'll have the chance to try it out in Frankfurt, Germany on my next business trip. It's kept me from getting completely lost on more than a dozen occasions.

That's all fine and dandy, but just how accurate is the GPS for tracking your current location?

I did a little test today by walking around the block at my office in downtown Portland. The trip around the block is exactly 0.2 miles, and I took screenshots of the iPhone every few seconds while the GPS tracked my position.

Then I put the screenshots together into a video using Camtasia (which I highly recommend), and uploaded the video to YouTube.

As you can see in the video, the GPS tracking system did a pretty good job of tracking my movements around the block.

I notice that the iPhone GPS is much more accurate than the Google map system that was built into my old Blackberry Curve with built-in GPS. There were many times where the BB GPS would show my current location in the middle of a river or freeway, even though I was several blocks away from those areas. I don't have that problem with the iPhone GPS.

If your GPS can't find your current location, make sure you're not in an underground tunnel or subway. In some cases you might need to power off your iphone and turn it back on to get the GPS working again (something I had to do on a recent trip to Colorado Springs).

Was your Curve also from AT&T, or another provider? Network availability might be affecting your GPS accuracy more than the built-in GPS receiver on your device. For example, Verizon blocks application access to the GPS equipment on their cell towers unless the Verizon customer has subscribed to an additional GPS navigation service like VZNavigator ($10/month). If you google "Verizon BlackBerry GPS" you will find hundreds of postings from irate Verizon customers who cannot use their BlackBerry's otherwise fully functional GPS receiver. Because of this "feature" I suspect that GPS-enabled phones from non-Verizon providers might lose their GPS capabilities whenever they roam onto the Verizon network, forcing Google Maps to revert to tower triangulation for pinpointing your location. This would account for your BB's occasional location discrepancies, and why turning your iPhone off and on often "fixes" your GPS, as this would force the iPhone to look for nearby AT&T cell towers as it starts up. Has anyone ever noticed a correlation between GPS inaccuracy and network roaming on their BlackBerry?

My curve was from AT&T. Man, that sucks about Verizon, and wreaks of greed, plain and simple.

Thanks for the insights into how roaming into "Verizon territory" could be causing the problems I was experiencing with GPS not working.

Thank you for writing your article. It helped me fix my GPS current location stall. All I had to do, due to learning from your article, is power off and on my iPhone.

Much Appreciation...


thanks for the input, i'm tracking a cheater and he swears the thing lied each and everytime

Ricky, Great write up on the iPhone GPS system. I too like the iPhone gps app over the Google Maps GPS. Your YouTube videos in the article were great. I have been using an iPhone gps for a while now. I wasn't too sure about getting rid of my gps and using just my iPhone, but it worked out great. I never thought my iPhone would replace all my other gps systems with such ease. I can't give enough parse for iPhone's hard work with doing things like GPS tracking.

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