A method for transmit timestamp autocalibration includes generating a calibration pulse for calibrating a transmit timestamp in a transmitting device. The method further includes applying the calibration pulse to a transmit data pipeline in the transmitting device. The method further includes sampling a transmit timestamp when the calibration pulse reaches a timestamp sample triggering location in the transmit data pipeline upstream from an egress point of the transmitting device. The method further includes measuring a latency between a time that the calibration pulse reaches the timestamp sample triggering location and a time that the calibration pulse reaches a location downstream from the timestamp sample triggering location. The method further includes generating an adjusted timestamp based on the measured latency and inserting the adjusted timestamp into a data packet to be transmitted from the transmitting device.