The disclosure relates to time of flight calculations for a lidar transceiver. Example embodiments include a method of calculating time of flight of a lidar signal, the method comprising: i) transmitting a light pulse to start (502) an acquisition time period having a plurality of successive time portions; ii) for each successive time portion, if a photon is received (503): iia) recording (505) a time at which the photon is received; iib) updating (504) a histogram to record a cumulative count of photons received during the time portion; iic) calculating (505) a time difference between the time at which the photon is received relative to a reference point of the time portion; iid) updating (506) a cumulative total of the calculated time difference for the time portion; iii) repeating steps i) to iid) for a succession of N transmitted light pulses; iv) identifying (509) a peak in a time portion of the histogram; and v) estimating (510) a time of flight from the cumulative total of the calculated time difference for the time portion of the histogram containing the identified peak.