Length vs. Weight Conversion Tables

A gar is a unique critter. The standard fisherman's weight calculation, girth^2*length/800, does not work well for these beaked fish. These tables will help you get a rough estimate of what that fish weighs.

Got GASS?
The original longnose length/weight info came from:
Netcsh, N. F., and A. Witt, Jr. 1962. Contributions to the life history of the longnose gar (Lepisosteus osseus) in Missouri. Trans. Amer. Fish. Soc. 91:251-262.

The equation they used was: log W = -7.0670 + 3.5075 log L (Weight in grams and length in mm)
A newer study, from South Dakota State in 2000, was developed expressly for the purpose of creating standard weight formulae of certain non-game species. They derived the equation (mm-grams): log W = -6.811 + 3.449 log L
The numbers look close, but since they are log functions, it amounts to quite a bit of difference. I'm including both in the table, converted to inches and pounds.

Table 1
Longnose Gar Length/Weight Lookup

Length (in.) Weight (lb.)1962 FormulaWeight (lb.)2000 Formula
36 4.65.6
375.16.1
38 5.66.7
39 6.17.3
406.78.0
41 7.38.7
427.99.5
43 8.610.3
449.311.1
45 10.112.0
4610.912.9
47 11.713.9
4812.615.0
49 13.616.1
5014.617.2
51 15.618.5
5216.719.7
53 17.921.1
5419.122.5
55 20.324.0
5621.725.5
57 2327.1
5824.528.8
59 26.030.5
6027.632.3

The same 2000 study included a formula for spotted gar in English inches and pounds and rearranged, W = 10^(-4.388 + 3.431 log L)

Table 2
Spotted Gar Length/Weight Lookup

Length (in.) Weight (lb.)
30 4.8
315.4
32 6.0
33 6.6
347.4
35 8.1
368.9
37 9.8
3810.8
39 11.8
4012.8
41 14.0
4215.2
43 16.5
4417.8
45 19.2
4620.7
47 22.3
4824.0
49 25.8
5027.6
51 29.6
5231.6
53 33.7
5436.0

A Michigan DNR publication covered a formula for shortnose gar in English inches and pounds and rearranged, W = 10^(-3.8730 + 2.9811 log L)

Table 2
Shortnose Gar Length/Weight Lookup

Length (in.) Weight (lb.)
25 2.0
262.2
27 2.5
282.8
29 3.1
303.4
31 3.7
324.1
33 4.5
344.9
35 5.4
365.8
37 6.3
386.9
39 7.4
408.0
41 8.6
429.2

A 2009 graduate thesis by by Kayla C. DiBenedetto, Louisiana State University, December 2009 Life History Characteristics Of Alligator Gar Atractosteus Spatula In The Bayou Dularge Area Of Southcentral Louisiana developed this formula (mm-gram) for both male and female gar: log(W) = - 5.4127 + 3.0513 log(L)
The table is converted to inches and pounds.

Table 1
Alligator Gar Length/Weight Lookup

Length (in.) Weight (lb.)
48 22
5025
52 28
54 32
5636
58 40
6044
62 49
6454
66 59
6864
70 70
7277
74 83
7690
78 98
80106
82 114
84123
86 132
88141
90 151
92 162
94173
96 184
98196
100 209
102222
104 235
106249

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