Anchor Rode Length Calculator

About this calculator

This calculator determines how much anchor rode — chain, rope, or a combination of the two — to let out using the standard boating formula: rode length = (water depth + bow height above the waterline) × scope ratio. Measuring depth from the bottom to the bow roller, not just to the surface, matters because that's where the rode actually starts.

Scope is the ratio of rode length to that total vertical distance; a typical overnight anchorage uses a 5:1 to 7:1 scope for adequate holding, while a low-angle pull in storm conditions calls for 8:1 or even 10:1 to keep the anchor shank pulling nearly horizontal instead of yanking it up out of the seabed. Sailors and boat owners use this to avoid the two failure modes of anchoring: dragging from too little scope, or swinging into neighbours from too much.