How to weigh your fish with a ruler

Fish Biologists have collected vast quantities of length and weight data from a variety of fish species. This has enabled length and weight relationships to be calculated for some fish species which can be used to estimate weight of a fish by measuring its length. Please note that these figures are estimates only and individual fish weight will vary depending on age, sex, season and recent feeding activity.

Measuring length

In some of the conversion tables, fork length measurements have been used while in others, total length has been used.

Fork length is measured from the snout to the fork of the tail.

Total length (legal length) is measured from the snout to the tip of the tail.

Fork length and total length of fish

Yellowfin bream

Please note: The following table has fork length measurements.

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
25	0.4	48	2.7
26	0.4	49	2.9
27	0.5	50	3.1
28	0.5	51	3.2
29	0.6	52	3.4
30	0.7	53	3.6
31	0.7	54	3.8
32	0.8	55	4.1
33	0.9	56	4.3
34	1.0	57	4.5
35	1.0	58	4.8
36	1.1	59	5.1
37	1.2	60	5.3
38	1.3	61	5.5
39	1.5	62	5.8
40	1.6	63	6.1
41	1.7	64	6.4
42	1.8	65	6.7
43	1.9	66	7.1
44	2.1	67	7.3
45	2.2	68	7.7
46	2.4	69	8.0
47	2.5	70	8.4

Reference: Steffe, A.S., Murphy, J.J., Chapman, D.J., Tarlinton, B.E. and Grinberg, A. 1996. An assessment of the impact of offshore recreational fishing in NSW waters on the management of commercial fisheries. FRDC Project no. 94/053. Publishers, Fisheries Research Institute, NSW Fisheries. 139pp.

Yellowtail Kingfish

Please note: The following table has fork length measurements.

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
60	2.8	94	10.6
61	2.9	96	11.3
62	3.0	98	12.0
63	3.2	100	12.8
64	3.4	105	14.8
65	3.5	110	17.0
66	3.7	115	19.4
67	3.8	120	22.0
68	4.0	125	24.9
69	4.2	130	28.0
70	4.4	135	31.4
71	4.6	140	35.0
72	4.8	145	38.9
73	5.0	150	43.0
74	5.2	155	47.5
76	5.6	160	52.0
78	6.1	165	57.3
80	6.5	170	62.6
82	7.0	175	68.3
84	7.6	180	74.3
86	8.1	185	80.7
88	8.7	190	87.4
90	9.3	195	94.5
92	9.9	200	101.9

Reference: Stewart, J., D. J. Ferrell, B. van der Walt, D. Johnson,and M. Lowry. 2002. Assessment of length and age composition of commercial kingfish landings. Final report to the Fisheries Research and Development Corporation, Project No. 97/126. NSW Fisheries, Cronulla.

Snapper

Please note: The following table has fork length measurements.

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
30	0.6	62	4.5
31	0.7	64	4.9
32	0.7	66	5.4
33	0.8	68	5.8
34	0.9	70	6.3
35	0.9	72	6.9
36	1.0	74	7.4
37	1.1	76	8.0
38	1.2	78	8.6
39	1.3	80	9.2
40	1.3	82	9.8
42	1.5	84	10.5
44	1.7	86	11.2
46	2.0	88	12.0
48	2.2	90	12.7
50	2.5	92	13.5
52	2.8	94	14.4
54	3.1	96	15.2
56	3.4	98	16.1
58	3.8	100	17.1
60	4.1

Reference: Moran M. J. and C. Burton. 1990. Relationships among partial and whole lengths and weights for Western Australian pink snapper Chrysophys auratus ( Sparidae). Fisheries Department of Western Australia, Fisheries Research Report No. 89.

Mulloway

Please note: The following table has total length measurements.

Total Length (cm)	Weight (kg)	Total Length (cm)	Weight (kg)
45	1.0	112	14.4
46	1.1	116	16.0
48	1.2	120	17.6
50	1.3	124	19.4
52	1.5	128	21.4
54	1.7	130	22.3
56	1.9	135	24.9
58	2.1	140	27.7
60	2.3	145	30.8
64	2.8	150	34.0
68	3.3	155	37.4
72	3.9	160	41.1
76	4.6	165	45.0
80	5.4	170	49.1
84	6.2	175	53.5
88	7.1	180	58.1
92	8.1	185	63.0
96	9.2	190	68.1
100	10.3	195	73.5
104	11.6	200	79.2
108	12.9

Dusky Flathead

Please note: The following table has total length measurements.

Total Length (cm)	Weight (kg)	Total Length (cm)	Weight (kg)
36	0.3	72	2.7
37	0.3	74	2.9
38	0.3	76	3.2
39	0.4	78	3.5
40	0.4	80	3.8
41	0.4	82	4.1
42	0.5	84	4.4
43	0.5	86	4.8
44	0.6	88	5.1
45	0.6	90	5.5
46	0.6	92	5.9
47	0.7	94	6.4
48	0.7	96	6.8
49	0.8	98	7.3
50	0.8	100	7.8
52	0.9	105	9.1
54	1.1	110	10.6
56	1.2	115	12.2
58	1.3	120	14.0
60	1.5	125	15.9
62	1.7	130	18.1
64	1.8	135	20.4
66	2.0	140	23.0
68	2.2	145	25.7
70	2.5	150	28.7

Australian Bass

Please note: The following table has fork length measurements.

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
25	0.3	43	1.6
26	0.3	44	1.7
27	0.4	45	1.8
28	0.4	46	1.9
29	0.5	47	2.0
30	0.5	48	2.2
31	0.6	49	2.3
32	0.6	50	2.5
33	0.7	51	2.6
34	0.8	52	2.8
35	0.8	53	2.9
36	0.9	54	3.1
37	1.0	55	3.3
38	1.1	56	3.5
39	1.2	57	3.7
40	1.3	58	3.9
41	1.3	59	4.1
42	1.5	60	4.3

Reference: Harris, J. H. 1987. Growth of Australian bass, Macquaria novemaculeata (Perciformes, Percichthyidae), in the Sydney basin. Australian Journal of Marine and Freshwater Research 38:351-361.

Murray cod

Please note: The following table has total length measurements.

Total Length (cm)	Weight (kg)	Total Length (cm)	Weight (kg)
40	1.1	72	7.6
42	1.3	74	8.3
44	1.5	76	9.0
46	1.8	78	9.8
48	2.0	80	10.7
50	2.3	82	11.6
52	2.6	84	12.5
54	3.0	86	13.5
56	3.3	88	14.6
58	3.7	90	15.7
60	4.2	92	16.8
62	4.6	94	18.0
64	5.2	96	19.3
66	5.7	98	20.7
68	6.3	100	22.1
70	6.9

Sand whiting

Please note: The following table has fork length measurements.

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
25	0.1	38	0.4
26	0.1	39	0.5
27	0.2	40	0.5
28	0.2	41	0.5
29	0.2	42	0.6
30	0.2	43	0.6
31	0.2	44	0.7
32	0.3	45	0.7
33	0.3	46	0.8
34	0.3	47	0.8
35	0.3	48	0.9
36	0.4	49	0.9
37	0.4	50	1.0

Tailor

Please note: The following table has fork length measurements.

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
30	0.3	56	2.5
32	0.4	58	2.8
34	0.5	60	3.0
36	0.6	62	3.4
38	0.7	64	3.8
40	0.9	66	4.2
42	1.0	68	4.6
44	1.2	70	5.0
46	1.3	72	5.5
48	1.5	74	6.0
50	1.7	76	6.5
52	1.9	78	7.1
54	2.2	80	7.7

Golden perch

Please note: The following table has fork length measurements.

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
30	0.4	41	1.2
31	0.5	42	1.3
32	0.5	43	1.4
33	0.6	44	1.5
34	0.7	45	1.6
35	0.7	46	1.7
36	0.8	47	2.0
37	0.9	48	2.2
38	1.0	49	2.5
39	1.0	50	2.6
40	1.1	51	2.8

Trout

Please note: The following table has fork length measurements.

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
27	0.3	51	1.8
29	0.3	53	2.0
31	0.4	55	2.3
33	0.5	57	2.5
35	0.6	59	2.8
37	0.7	61	3.1
39	0.8	63	3.4
41	0.9	65	3.7
43	1.1	67	4.1
45	1.2	69	4.4
47	1.4	71	4.8
49	1.6	73	5.3

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
25	0.4	48	2.7
26	0.4	49	2.9
27	0.5	50	3.1
28	0.5	51	3.2
29	0.6	52	3.4
30	0.7	53	3.6
31	0.7	54	3.8
32	0.8	55	4.1
33	0.9	56	4.3
34	1.0	57	4.5
35	1.0	58	4.8
36	1.1	59	5.1
37	1.2	60	5.3
38	1.3	61	5.5
39	1.5	62	5.8
40	1.6	63	6.1
41	1.7	64	6.4
42	1.8	65	6.7
43	1.9	66	7.1
44	2.1	67	7.3
45	2.2	68	7.7
46	2.4	69	8.0
47	2.5	70	8.4

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
25	0.3	43	1.6
26	0.3	44	1.7
27	0.4	45	1.8
28	0.4	46	1.9
29	0.5	47	2.0
30	0.5	48	2.2
31	0.6	49	2.3
32	0.6	50	2.5
33	0.7	51	2.6
34	0.8	52	2.8
35	0.8	53	2.9
36	0.9	54	3.1
37	1.0	55	3.3
38	1.1	56	3.5
39	1.2	57	3.7
40	1.3	58	3.9
41	1.3	59	4.1
42	1.5	60	4.3

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
25	0.1	38	0.4
26	0.1	39	0.5
27	0.2	40	0.5
28	0.2	41	0.5
29	0.2	42	0.6
30	0.2	43	0.6
31	0.2	44	0.7
32	0.3	45	0.7
33	0.3	46	0.8
34	0.3	47	0.8
35	0.3	48	0.9
36	0.4	49	0.9
37	0.4	50	1.0

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
30	0.3	56	2.5
32	0.4	58	2.8
34	0.5	60	3.0
36	0.6	62	3.4
38	0.7	64	3.8
40	0.9	66	4.2
42	1.0	68	4.6
44	1.2	70	5.0
46	1.3	72	5.5
48	1.5	74	6.0
50	1.7	76	6.5
52	1.9	78	7.1
54	2.2	80	7.7

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
30	0.4	41	1.2
31	0.5	42	1.3
32	0.5	43	1.4
33	0.6	44	1.5
34	0.7	45	1.6
35	0.7	46	1.7
36	0.8	47	2.0
37	0.9	48	2.2
38	1.0	49	2.5
39	1.0	50	2.6
40	1.1	51	2.8

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
27	0.3	51	1.8
29	0.3	53	2.0
31	0.4	55	2.3
33	0.5	57	2.5
35	0.6	59	2.8
37	0.7	61	3.1
39	0.8	63	3.4
41	0.9	65	3.7
43	1.1	67	4.1
45	1.2	69	4.4
47	1.4	71	4.8
49	1.6	73	5.3

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
25	0.4	48	2.7
26	0.4	49	2.9
27	0.5	50	3.1
28	0.5	51	3.2
29	0.6	52	3.4
30	0.7	53	3.6
31	0.7	54	3.8
32	0.8	55	4.1
33	0.9	56	4.3
34	1.0	57	4.5
35	1.0	58	4.8
36	1.1	59	5.1
37	1.2	60	5.3
38	1.3	61	5.5
39	1.5	62	5.8
40	1.6	63	6.1
41	1.7	64	6.4
42	1.8	65	6.7
43	1.9	66	7.1
44	2.1	67	7.3
45	2.2	68	7.7
46	2.4	69	8.0
47	2.5	70	8.4

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
25	0.3	43	1.6
26	0.3	44	1.7
27	0.4	45	1.8
28	0.4	46	1.9
29	0.5	47	2.0
30	0.5	48	2.2
31	0.6	49	2.3
32	0.6	50	2.5
33	0.7	51	2.6
34	0.8	52	2.8
35	0.8	53	2.9
36	0.9	54	3.1
37	1.0	55	3.3
38	1.1	56	3.5
39	1.2	57	3.7
40	1.3	58	3.9
41	1.3	59	4.1
42	1.5	60	4.3

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
25	0.1	38	0.4
26	0.1	39	0.5
27	0.2	40	0.5
28	0.2	41	0.5
29	0.2	42	0.6
30	0.2	43	0.6
31	0.2	44	0.7
32	0.3	45	0.7
33	0.3	46	0.8
34	0.3	47	0.8
35	0.3	48	0.9
36	0.4	49	0.9
37	0.4	50	1.0

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
30	0.3	56	2.5
32	0.4	58	2.8
34	0.5	60	3.0
36	0.6	62	3.4
38	0.7	64	3.8
40	0.9	66	4.2
42	1.0	68	4.6
44	1.2	70	5.0
46	1.3	72	5.5
48	1.5	74	6.0
50	1.7	76	6.5
52	1.9	78	7.1
54	2.2	80	7.7

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
30	0.4	41	1.2
31	0.5	42	1.3
32	0.5	43	1.4
33	0.6	44	1.5
34	0.7	45	1.6
35	0.7	46	1.7
36	0.8	47	2.0
37	0.9	48	2.2
38	1.0	49	2.5
39	1.0	50	2.6
40	1.1	51	2.8

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
27	0.3	51	1.8
29	0.3	53	2.0
31	0.4	55	2.3
33	0.5	57	2.5
35	0.6	59	2.8
37	0.7	61	3.1
39	0.8	63	3.4
41	0.9	65	3.7
43	1.1	67	4.1
45	1.2	69	4.4
47	1.4	71	4.8
49	1.6	73	5.3

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
25	0.4	48	2.7
26	0.4	49	2.9
27	0.5	50	3.1
28	0.5	51	3.2
29	0.6	52	3.4
30	0.7	53	3.6
31	0.7	54	3.8
32	0.8	55	4.1
33	0.9	56	4.3
34	1.0	57	4.5
35	1.0	58	4.8
36	1.1	59	5.1
37	1.2	60	5.3
38	1.3	61	5.5
39	1.5	62	5.8
40	1.6	63	6.1
41	1.7	64	6.4
42	1.8	65	6.7
43	1.9	66	7.1
44	2.1	67	7.3
45	2.2	68	7.7
46	2.4	69	8.0
47	2.5	70	8.4

Fork Length (cm)	Weight (kg)	Fork Length (cm)	Weight (kg)
25	0.3	43	1.6
26	0.3	44	1.7
27	0.4	45	1.8
28	0.4	46	1.9
29	0.5	47	2.0
30	0.5	48	2.2
31	0.6	49	2.3
32	0.6	50	2.5
33	0.7	51	2.6
34	0.8	52	2.8
35	0.8	53	2.9
36	0.9	54	3.1
37	1.0	55	3.3
38	1.1	56	3.5
39	1.2	57	3.7
40	1.3	58	3.9
41	1.3	59	4.1
42	1.5	60	4.3

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
25	0.1	38	0.4
26	0.1	39	0.5
27	0.2	40	0.5
28	0.2	41	0.5
29	0.2	42	0.6
30	0.2	43	0.6
31	0.2	44	0.7
32	0.3	45	0.7
33	0.3	46	0.8
34	0.3	47	0.8
35	0.3	48	0.9
36	0.4	49	0.9
37	0.4	50	1.0

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
30	0.3	56	2.5
32	0.4	58	2.8
34	0.5	60	3.0
36	0.6	62	3.4
38	0.7	64	3.8
40	0.9	66	4.2
42	1.0	68	4.6
44	1.2	70	5.0
46	1.3	72	5.5
48	1.5	74	6.0
50	1.7	76	6.5
52	1.9	78	7.1
54	2.2	80	7.7

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
30	0.4	41	1.2
31	0.5	42	1.3
32	0.5	43	1.4
33	0.6	44	1.5
34	0.7	45	1.6
35	0.7	46	1.7
36	0.8	47	2.0
37	0.9	48	2.2
38	1.0	49	2.5
39	1.0	50	2.6
40	1.1	51	2.8

Fork length(cm)	Weight (kg)	Fork length(cm)	Weight (kg)
27	0.3	51	1.8
29	0.3	53	2.0
31	0.4	55	2.3
33	0.5	57	2.5
35	0.6	59	2.8
37	0.7	61	3.1
39	0.8	63	3.4
41	0.9	65	3.7
43	1.1	67	4.1
45	1.2	69	4.4
47	1.4	71	4.8
49	1.6	73	5.3