How Much Do King Salmon Weigh? A Detailed Look at Estimating and Converting King Salmon Weights

Anglers love king salmon, which are also called Chinook salmon, because they are so big and willing to fight. But how much do these huge fish really weigh? It can be hard to guess and convert the weight of a king salmon based on its length and width without the right tools and methods. This in-depth article will show you how to figure out the weight of a king salmon so that you can get a better idea of how big your catch really is.

Average Weight of King Salmon

Most adult king salmon weigh between 15 and 50 pounds, but the biggest ones can weigh 100 pounds or more. However, average weights can be very different depending on the river system and region.

For example, king salmon from Alaska’s famous Kenai River weigh about 20 to 40 pounds on average. King salmon from the Columbia River between Oregon and Washington, on the other hand, usually weigh between 15 and 25 pounds. The biggest king salmon ever caught was 126 pounds and came from Alaska’s Kenai River in 1985.

Length-to-Weight Conversion Formulas

Since weighing a landed king salmon directly is not always feasible formulas exist to estimate weight based on the fish’s length and girth measurements.

One such formula is

Weight (lbs) = Length (in) x Girth (in) x Girth (in) / 800

Where length equals the total length from nose to tail in inches, and girth equals the thickest part of the body in inches.

This formula provides a rough estimate but tends to be most accurate for shorter fish under 40 inches. For larger kings the following formula is often more precise

Weight (lbs) = Girth (in)^2 x Length (in) / 800

Making sure to carefully measure total length and maximum girth will lead to the most accurate weight estimates when applying these formulas in the field.

King Salmon Length-Weight Conversion Charts

Length-weight conversion charts are another handy resource for estimating the weight of a landed king salmon based on its length. Here is an example chart:

King Salmon Length (in) – Estimated Weight (lbs)

• 25 – 6
• 30 – 11
• 35 – 17
• 40 – 25
• 45 – 35
• 50 – 48
• 55 – 64
• 60 – 82

These charts provide a quick reference for weight estimates categorized across the most common king salmon length ranges. However, it is important to note they represent above-average weights, not absolute averages. Outlier skinny or fat fish may weigh noticeably less or more.

Regional Length-Weight Standards

Generic conversion formulas and charts provide reasonable estimates, but using region-specific length-weight data often improves accuracy.

For example, the Alaska Department of Fish and Game compiles custom length-weight charts for major salmon fishing rivers like the Kenai and Copper. Biologists collect actual weight data from sampled fish to create tailored conversion charts reflecting the unique size profiles of that river system.

Checking for a regional length-weight chart can remove the need to guesswork when estimating your catch weight on specific rivers.

Additional Weight Estimating Tips

Here are some additional tips for dialing in weight estimates of a prized king salmon:

• Measure carefully – Precision when measuring total length and girth leads to the most accurate weight calculations. Use a reliable measuring tape or marked rod.

• Consider body shape – Stocky, thick-bodied fish weigh more than slender ones of the same length. Adjust estimates up or down accordingly.

• Factor in maturity – Full adult spawners with pronounced kypes (hooked jaws) tend to weigh more than younger, immature fish at equal lengths.

• Note condition – Healthy, robust fish weigh more than skinny or worn-down fish. Take fish condition into your estimate.

• Use ice weight – Weighing your catch after icing it down provides the most certain weight, even if applying formulas after the fact.

While formulas, charts, and techniques provide estimates, actually weighing your catch is the only surefire method. But armed with the information above, anglers can now make much more educated guesses regarding the weight of a trophy king salmon they successfully land. Dialing in accurate weight estimates will lead to better record keeping and a fuller appreciation of the sheer size these iconic fish can attain.