How is coords.accuracy measured, what unit is it in?

How is coords.accuracy measured, what unit is it in?

The goal is to use it to determine a radius of error when finding a location.

How accurate is GPS latitude and longitude?

It is comparable to the typical accuracy of an uncorrected GPS unit with no interference. The fifth decimal place is worth up to 1.1 m: it distinguish trees from each other. Accuracy to this level with commercial GPS units can only be achieved with differential correction.

It is typically expressed in meters.

The Geolocation API specified by W3C says:

The accuracy attribute denotes the accuracy level of the latitude and longitude coordinates. It is specified in meters and must be supported by all implementations. The value of the accuracy attribute must be a non-negative real number.

It's meters for PhoneGap, Google's various geo APIs, and so on. It's almost certain that meters are the unit of measurement in whatever you're using.