How deep does each color of lead core go?

A common rule of thumb is about 5 feet of depth per 10-yard color at a typical 2 mile-per-hour trolling speed, before any leader. So five colors run roughly 25 feet down. Slower speeds let it sink deeper; faster speeds lift it shallower.

What is a color of lead core line?

Lead core line is dyed in repeating 10-yard segments of different colors so you can count how much line is out at a glance. Each color you let out adds a predictable amount of depth, which is why anglers talk about fishing a lure at a number of colors rather than feet.

How does trolling speed change depth?

Faster trolling creates more drag on the line and lure, lifting them toward the surface, while slower trolling lets everything sink deeper. This calculator scales the base depth by your speed relative to a 2 mile-per-hour reference, so a 3 mph troll runs noticeably shallower.

Why does line diameter matter for braid and mono?

Thinner line cuts through the water with less drag and dives deeper for the same amount of line out, while thick line planes upward. The diameter factor in the braid and mono model rewards thin braid with extra depth, matching how dipsy and flat-line setups behave in practice.

Should I account for the leader and lure?

Yes. These estimates are for the line itself; a long mono leader floats and reduces depth, while a heavy diving crankbait adds depth on its own. Treat the result as a baseline and fine-tune with a line counter and any strikes you get at known depths.

What is the Trolling Depth Calculator?

Estimate how deep your lure runs when trolling. Use the lead-core colors rule (about 5 feet per 10-yard color) or a line-out and speed model for braid and mono, adjusted for trolling speed. Built for walleye, salmon, and trout anglers. It runs free in your browser on Gera Tools, with nothing uploaded.

Trolling Depth Calculator

Name: Trolling Depth Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Getting your lure into the strike zone is the whole game in trolling. This calculator estimates lure depth two ways: the classic lead-core colors rule and a line-out, diameter, and speed model for braid or monofilament.

How it works

For lead core, each 10-yard color adds a fixed depth, scaled by speed:

leadCoreDepth (ft) = colors × 5 × speedFactor

For braid or mono, depth grows with line out, increases for thinner line, and is reduced by speed:

baseDepth   = lineOutFt × diveRate(diameter)
speedFactor = 2.0 / trollingSpeedMph   (capped to a sensible range)
depth (ft)  = baseDepth × speedFactor

The 2.0 mph reference is the speed at which the rule-of-thumb numbers are calibrated. Faster than that and the lure planes upward; slower and it sinks deeper. Thin braid dives more per foot of line than thick mono.

Lead core: colors to depth reference

Colors out	Depth at 1.5 mph	Depth at 2.0 mph	Depth at 3.0 mph
2	~13 ft	~10 ft	~7 ft
5	~33 ft	~25 ft	~17 ft
8	~53 ft	~40 ft	~27 ft
10	~67 ft	~50 ft	~33 ft

Approximate, based on the 5-ft-per-color rule at 2 mph calibration. Real depths vary by leader length, lure drag, and current.

Worked example — walleye on lead core

For example, you are targeting walleye holding at 22–26 feet on a mid-summer lake. At a 2 mph troll, five colors of lead core puts you at approximately 25 feet — right in the zone. Speed up to 2.5 mph and you rise to roughly 20 feet, potentially above the fish. Slow to 1.5 mph and you drop to about 33 feet — below them. Adjusting speed is a fast way to change depth without changing colors.

Braid and mono setup tips

Thin braid is the best deep-running flatline option. For example, 100 feet of 0.011-inch braid at 2 mph might run near 18 feet; the same amount of 0.020-inch mono runs several feet shallower due to increased water resistance.

When running braid, a mono or fluorocarbon leader of 20–40 feet is standard for stretch and abrasion resistance. A long mono leader floats and reduces depth — shorter leaders run deeper. Factor this in when targeting a precise depth range.

Key factors that change actual depth

Lure drag — a deep-diving crankbait adds several feet of its own depth action; a light spoon has little additional pull
Current — running into a current increases effective speed and lifts the lure; running with a current has the opposite effect
Line counter accuracy — a reliable line counter reel lets you duplicate a productive depth on every pass
Multiple rods — stagger colors or line-out amounts on different rods (for example 3, 5, and 7 colors) to find the productive zone quickly, then cluster rods around the winner