How accurate is the Apple iPhone GPS locator?

In tests performed by the geographic information company Esri, integrated iPhone GPS chips are accurate to 3 meters approximately 90 percent of the time in open sky conditions. In the same test, a standalone receiver connected to an iPhone is accurate to 3 meters approximately 99 percent of the time.

Professional-grade GPS locators perform better than both the iPhone and consumer-grade units in the same test. A commercial-grade product connected to an iPhone is accurate to 1 meter in 92 percent of Esri's tests. As of 2015, the consumer-grade unit is accurate to 1 meter only 70 percent of the time, and the integrated iPhone unit is not capable of accuracy to 1 meter.