Largemouth bass relative weight index
Relative weight (Wr) tells you whether the bass in your pond are healthy, thin, or trophy-ready. Measure a fish, run the numbers, and know where your population stands.
What relative weight tells you
Relative weight compares what a fish actually weighs to what a healthy, fast-growing fish of the same length should weigh, called the standard weight. The result is a simple percentage:
A bass has to be at or above 100% to keep growing longer. Trophy fish spend most of their lives at or above 100%. Average fish usually only cross 100% for a few months a year, and stunted, skinny fish rarely get there at all. Tracking Wr a few times a year is one of the easiest ways to see whether your bass are well fed and actively growing.
Relative weight calculator
Enter the length and weight of a bass you've caught. We'll find the standard weight for that length and calculate its Wr.
Your result will appear here.
Standard weight chart
The weight a healthy largemouth bass should hit at each length (100% relative weight). Find your fish's length, compare to its actual weight.
| Length | Standard weight (100%) | Length | Standard weight (100%) |
|---|---|---|---|
| 10" | 10 oz | 17" | 2 lb 13 oz |
| 11" | 11 oz | 17.5" | 3 lb 0 oz |
| 12" | 12 oz | 18" | 3 lb 4 oz |
| 12.5" | 15 oz | 18.5" | 3 lb 9 oz |
| 13" | 1 lb 2 oz | 19" | 3 lb 14 oz |
| 13.5" | 1 lb 4 oz | 19.5" | 4 lb 3 oz |
| 14" | 1 lb 7 oz | 20" | 4 lb 8 oz |
| 14.5" | 1 lb 10 oz | 20.5" | 4 lb 14 oz |
| 15" | 1 lb 13 oz | 21" | 5 lb 5 oz |
| 15.5" | 2 lb 0 oz | 21.5" | 5 lb 12 oz |
| 16" | 2 lb 4 oz | 22" | 6 lb 3 oz |
| 16.5" | 2 lb 8 oz | 23" | 7 lb 2 oz |
| 24" | 8 lb 3 oz | ||
Standard weights based on the Wege & Anderson (1978) largemouth bass equation used by fisheries biologists across North America. Fish vary seasonally; a healthy female can dip after spawning and recover by fall.
Reading a real fish
Say you catch a 15-inch bass that weighs 1.5 lbs. The chart shows a 15-inch bass should weigh about 1 lb 13 oz (1.81 lbs) at 100%.
1.5 ÷ 1.81 × 100 ≈ 83% Wr
That's on the thin side, within the healthy range, but a sign the pond may be carrying more bass than the forage can support. If most of your fish read like this, it's usually time for an electrofishing survey and a management plan.
See our survey services →Bass reading thin?
If your relative weights are low across the board, we can survey your pond, find what's out of balance, and build a plan to fix it.