Tools
Fish Weight Calculator: Muskie and Northern Pike
Measure the fish, let it go, and work out the weight afterward. Enter the length for a quick estimate. Add the girth, measured around the thickest part of the body, for a closer one.
How to measure
Length is the total length: tip of the closed mouth to the tip of the tail, with the tail pinched together. Girth is the distance around the body at its thickest point. Keep the fish in the water or in the net while you measure, and use a soft tape for the girth.
Muskie: weight by length
Two published curves, and they do not agree. Wisconsin DNR gives the weight of anaverage muskie at four lengths. The chart most anglers know is the standard-weight equation of Neumann and Willis, built from 4,343 fish in 16 states, which by design describes a well-fed fish, heavier than three in four muskies of that length. The calculator uses the standard-weight equation and says so; expect an average fish to come in lighter.
| Length | Well-fed fish (standard weight) | Average fish (Wisconsin DNR) |
|---|---|---|
| 30 in (76 cm) | 7.2 lb (3.3 kg) | Not published |
| 34 in (86 cm) | 11.0 lb (5.0 kg) | 10 lb at 33 in |
| 36 in (91 cm) | 13.3 lb (6.0 kg) | Not published |
| 40 in (102 cm) | 18.8 lb (8.5 kg) | 20 lb at 41 in |
| 42 in (107 cm) | 22.1 lb (10.0 kg) | Not published |
| 45 in (114 cm) | 27.9 lb (12.6 kg) | Not published |
| 48 in (122 cm) | 34.5 lb (15.7 kg) | 30 lb at 47 in |
| 50 in (127 cm) | 39.5 lb (17.9 kg) | Not published |
| 52 in (132 cm) | 45.1 lb (20.4 kg) | 40 lb at 52 in |
| 54 in (137 cm) | 51.1 lb (23.2 kg) | Not published |
| 56 in (142 cm) | 57.6 lb (26.1 kg) | Not published |
Length alone flatters a very long fish. The equation gives 64.8 lb for a 58 in muskie; Joe Seeberger's 58 in Michigan fish of 2012 weighed 58 lb on a certified scale, and Nolan Sprengeler's 57¾ in Minnesota record of 2021 weighed 55 lb 14.8 oz. Above about 50 in, measure the girth.
Muskie: weight by length and girth
With inches and pounds, three formulas are in use:
- Standard: length × girth × girth ÷ 800. A general formula from the 1920s, built on saltwater fish.
- Crawford: (length × girth ÷ 25) − 10. Published for muskies in 2002 from several hundred fish, most under 50 lb.
- Modified Crawford: (length × girth ÷ 25) − 8. Larry Ramsell's 2017 adjustment for the giants, from 27 weighed fish of 50 to 61 lb.
| Weighed fish | Standard | Crawford | Modified Crawford |
|---|---|---|---|
| Seeberger, 58 × 29 in, 58.0 lb | 61.0 lb | 57.3 lb | 59.3 lb |
| Sprengeler, 57¾ × 29 in, 55.9 lb | 60.7 lb | 57.0 lb | 59.0 lb |
On those two certified fish the Crawford formula lands closest and the standard formula runs three to five pounds heavy. The calculator shows all three for a muskie so you can see the spread; treat the answer as good to within a few pounds.
Northern pike: weight by length
North Dakota Game and Fish publishes the average weight of its pike at every length, from real fish statewide. The calculator reads this table and fills in the lengths between the rows. A female full of eggs before the spawn weighs more than the table says.
| Length | Average weight |
|---|---|
| 20 in (51 cm) | 1.8 lb (0.8 kg) |
| 24 in (61 cm) | 3.2 lb (1.5 kg) |
| 28 in (71 cm) | 5.1 lb (2.3 kg) |
| 30 in (76 cm) | 6.3 lb (2.9 kg) |
| 32 in (81 cm) | 7.7 lb (3.5 kg) |
| 34 in (86 cm) | 9.2 lb (4.2 kg) |
| 36 in (91 cm) | 11.0 lb (5.0 kg) |
| 38 in (97 cm) | 13.0 lb (5.9 kg) |
| 40 in (102 cm) | 15.2 lb (6.9 kg) |
| 42 in (107 cm) | 17.6 lb (8.0 kg) |
| 44 in (112 cm) | 20.3 lb (9.2 kg) |
| 46 in (117 cm) | 23.2 lb (10.5 kg) |
| 48 in (122 cm) | 26.5 lb (12.0 kg) |
| 50 in (127 cm) | 30.0 lb (13.6 kg) |
No girth formula has been published for pike specifically. When you enter a girth for a pike, the calculator adds the standard formula (length × girth × girth ÷ 800) beside the table value, labeled as a general estimate.
What the number is worth
Every figure here is an estimate from averages. Two fish of the same length can differ by pounds with the season, the lake and what they ate last week. For a record claim only a certified scale counts. For a released fish, length and girth and a photo are the honest record, and this page turns them into a fair number.
Go deeper
- Muskie: how old a 40 or 50 in fish is, and the records behind these numbers.
- Northern pike: size by age, teeth, and where the big ones go in summer.
- Pike, muskie and pickerel: the family told apart.
Sources
- North Dakota Game and Fish, Fish length-weight table
- Wisconsin DNR, Muskellunge Management Update (2012): average weight at length
- Rob Neumann, Muskie length to weight conversion chart, In-Fisherman (2016)
- Neumann and Willis (1994), Relative weight as a condition index for muskellunge, Journal of Freshwater Ecology 9(1)
- Larry Ramsell, New formula for estimating released muskellunge weight, OutdoorsFirst (2019)
- Michigan DNR (2013), State-record Great Lakes muskellunge now also a world record
- Fox 9 (2021), Minnesota DNR certifies 55-pound muskie caught on Mille Lacs Lake as new record