The seat is 15.5" wide and 11" front to back. The hole pattern on this bike seat is a 4 hole pattern.  The holes are spaced 5.75" apart left to right and 5" apart front to back.  All holes are measured fron the center on one hole to the center of the other hole.  The holes each have a 6-1.0 mm threaded insert.

NOTE: The seat base is wood, so if you needed a different hole pattern you could use this seat and put wood screw into the base.  PLEASE NOTE if you chose to put wood screws into the base we will consider this a modification and will not accept the part for a return.