Free fishing tool

Fish weight estimator

Estimate a fish’s weight from its species and total length. Enter a known length, or use a side-on photo with an object of known size to measure it.

Freshwater and sea speciesNo account requiredPhoto stays on your device

Create an estimate

For the best photo result, keep the fish straight and place the reference object beside it at the same distance from the camera.

1 · Species and scale

Fish species Known total length (cm)Use this if you already measured the fish. Or reference-object length (cm)Required when measuring from a photo. Display result in

Optional photo measurement

Mark both ends of the reference object, followed by the fish’s snout and tail.

2 · Photo

Choose a species and enter a known length, or add a photo.

How the estimate works

FishMap applies a species-specific length-to-weight relationship to the measured total length. Photo mode uses the known object to calculate the fish’s approximate length in the image.

The displayed range allows for differences in fish condition and photo measurement. It is not a substitute for weighing the fish with suitable, fish-safe equipment.

Measurement tips

Photograph the fish side-on and as straight as possible.
Keep the reference object level with the fish.
Avoid wide-angle distortion and strong perspective.
Measure rays wingtip-to-wingtip where the selected model states this.

Welfare first

Keep handling time short, support the fish properly and return it safely. The estimator is a planning and record-keeping aid, not a certified measurement.