In general, for all race distances, you can use whatever split distances you want as long as they are all the same split distance. For example, for any of the distances listed, you could enter 100m splits if you want instead of the listed split distances.

If you want to use splits for a race distance that's not listed, select "Pick a distance". In this case, all split distances must be the same. For example, to enter splits for a 5-mile race using 1-mile split distances, you'd pick "Pick a distance", then enter each mile split in seconds.