If you dont have a scale and just hooked into the big one, no worries. With the MyNature Fish Weight Calculator you only need to measure the length and girth of your catch to get an estimate thats within 10% of the fishs actual weight. The weight calculator couldnt be easier to use, simply select the species you caught on the wheel, enter the two measurements girth and length and hit calculate, its that easy. We also included a pop-up screen with fractions of an inch conversions so you can spend more time fishing and not doing math. Good luck on the water!!