The 1960-1970's era Tudor goalposts were four inches wide, and that's the standard that is used in most leagues and tournaments.  The goalpost crossbar is 1 7/8 inches from the field, so a kick is <strong>no good</strong> if it's below that.  In MFCA tournaments,  field goals are performed by the kicker lined up 7 yards behind the line of scrimmage,  with no defense,  and the board off.   The longest allowable field goal is identical to the NFL record: 64 yards.  Other leagues may have different rules. 
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Most leagues and tournaments offer automatic extra points, unless the offense chooses to try for a 2-point conversion.
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There are some creative ideas to help determine whether a field goal is good or not.  A simple 4-inch wide board is the usual field goal target.  I've seen a large poster board with a 4-inch wide cutout as the target. 
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My contribution to the hobby is the discovery that certain brands of scotch, such as Lagavulin, come in 4-inch boxes. :-)  I think my field goal target is the coolest.
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    Best Field Goal Posts Ever!
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