In one aspect, a method includes performing, by a wireless station, a fine timing measurement (FTM) procedure that includes exchanging one or more FTM messages between the wireless station and an access point to obtain a first round-trip time (RTT) between the wireless station and the access point. The method also includes performing, by the wireless station, a non-FTM procedure to obtain a second RTT between the wireless station and the access point. The wireless station then calculates a turn-around calibration factor (TCF) estimate of the access point based on a difference between the second RTT and the first RTT. Data representative of the TCF estimate of the access point may then be sent to a server.