Nelson's log

Observed iPhone location accuracy

Our Wanderings project uploads location fixes with the iOS significant location changes APIs. It includes an accuracy number, distance in meters, and occasionally we get points with accuracies > 1000m. We’re about to stop displaying those, but before I do here’s what the data looks like:

That shows most points have an accuracy of 10m, a significant number have an accuracy of 65m, and a few have 1414m. This histogram tool is misleading, there are also 15 points with an accuracy > 1414m. (Shout out to 7094 meters; you did your best, little iPhone).

If I had to guess, I’d say 1414m means “location from a single cell tower” and 65m means “location from a single wifi access point”. But who knows. It’s possible to ask the iPhone to give you more accurate fixes, we’re deliberately only using the most low power location monitoring to conserve battery life.