A TOA positioning system can be implemented that employs a calculated initial location of a wireless network device. For each of a plurality of reference wireless network devices, a distance between the wireless network device and the reference wireless network device is determined based, at least in part, on a round trip transit time between the wireless network device and the reference wireless network device. An initial location of the wireless network device can be calculated based, at least in part, on a location of each of the plurality of reference wireless network devices. A location of the wireless network device can be estimated based, at least in part, on the calculated initial location, the distance to each of the reference wireless network devices, and an initial distance calibration constant.