Using empirical data we obtained and MS Excel Regression analysis, the best formula we have for
estimating the weight of a bowfin is G^2*L/780 +0.75 = W, where G is the girth (circumference) in inches, L is the length in inches, and W is the weight in pounds. The
prediction factor is 0.96, with 0 meaning the formula doesn't predict
the data at all and 1 is a perfect prediction, so we are very close
with this formula.The values in Table 1 were calculated with this. The girths we found in our dataset, expressed as a fraction of the length ranged from a low of .42*L to a high of .57*L so I restricted my table to these limits.
If you have length only, the average girth is 0.492*L
making the formula L^3/3221 + 0.75 = W. The prediction factor drops to
0.90, still pretty good and enough to let you know if you are near a
state/class/world record that merits special attention. See Table 2 for
these values.


















