The standard IAAF track has curves that are semi-circular with a radius of 36.500M at the curb and 36.800 at the measuring line. Lanes are 1.22 meters wide. A easy rule of thumb for approx distances found in the Big Green Book is
add 6 ft of distance per lap for every foot out from the curb. Lane 4 is 16 feet out ie 1.22m. x4 so running a lap on a standard IAAF track in lane 4 is 430m give or take an amount that for training means nothing.
The non continious curve with 3 radii was actually used for some tracks but is not standard and I believe not allowed anymore.
All this blabber aside you are doing workouts. Details of a meter or half second +/- do not belong unless you are doing precise sprint pacing workouts. Say you run 4 miles in repeats of various lengths and reps, do you think your conditioning changes if you covered 4 miles and 41 yds or 3 miles and 1754 yards?
Call a lap in lane 4 a training lap and 4 laps a training mile and get over it.