Based on research, it was discovered that the  standard "length x girth, etc." formula was not very effective at determining an accurate estimate weight for tarpon.  Consequently, review of weight data for tarpon that had been killed and taken to the scales were analyzed, and a more accurate formula was developed to predict the weight of a tarpon, based on a tarpon's unique body shape.  While the formula is too complicated for most recreational anglers, Dr. Ault and his group at the University of Miami have developed the chart below, to help you estimate the weight of any tarpon you catch.  Simply use the fork length and the girth of your fish, map it in the graph and you'll get a more accurate estimate. 


Photo by Brent Huggins