Secure range estimates as described herein may include determining a range estimate between two Bluetooth enabled devices based, at least in part, on round trip phase measurements of wireless signals transmitted between the devices. In one example, a range estimate may include determining a first set of relative carrier measurements at a first set of frequencies, determining a second set of relative carrier measurements based on the first set at the second set of frequencies; and combining the first set and the second set to estimate a distance between the devices.