How It Works

This calculator is based on the desktop app made available by Chris Carlin of Far North Rodsmiths with his expressed permission. The goal is to take the same calculations the rod building community has used for ages and make them accessible from any device on the internet be it your phone, tablet, or PC.

The calculations are based on the Dale Clemen's and Jeffrey Baehre's original formula for calculating guide spacing. The equation is a guide spread calculation which derives a constant from the rod length and number of guides.

distance = ( n(t) + n(n - 1) d ) / 2

  • n = number of guides
  • t = distance from the tip top
  • d = calculated constant ratio for spacing

Other factors are considered such as line weight and the presence of a taming guide in order to provide a consistent sizing chart.

Note that you may have to make adjustments or add a guide should any guide land directly on a ferrule.

So, it's Free?

Yep, free. Those who build rods as a profession are a generous community. They share their knowledge and expertiese freely. So, the folks at Cutthroat Traders are happy to make this tool freely available. Oh, and it works on your smartphone or tablet too.


While I'm not always in front of my PC when I'm building a rod, I always have my smart phone or tablet next to me. I wanted a tool that would work anywhere, not just on my PC. The current downloadale app requires you be in front of a PC, and go through additional emulator headache if you're a Mac user.

With this site, the same calculations you're accustomed to are available on any device at any time. Simple as that. It's always on, always free, and I'm always open to suggestion if you can help make it beter.

Want me to improve something? Email me at