Fishing reel gear ratio

Change the spool size in the calculator and watch line per turn move while the ratio stays the same.

A gear ratio like 6.2:1 means the rotor (spinning) or spool (baitcast) turns 6.2 times for one turn of the handle. The line that comes in also depends on the spool’s diameter and how full it is, which is why makers list ratio and line per turn separately.1 2 3 4 5

One handle turn. How much line?

Start with this worked example. Change the spool diameter and watch the line per turn, keeping ratio and line depth steady.

Fig. 1 — Count turns, then line

Handle1 full turn

Rotor or spool6.2 turns

This drawing shows the relationship, not the dimensions of your reel. Each rotor or spool turn recovers one circumference at the line pack's diameter.

What does gear ratio mean?

How many times the rotor or spool turns for one turn of the handle, written like 6.2:1.1 2 3 4 5

Gear ratio in the glossary

Gear ratio6.2:1

For a ratio written 6.2:1, enter 6.2.

Spool rim diameter

Distance across the spool's outer rim. This model accepts 15–120 mm; changing units converts your value.

Line depth: core to rim90%

How far the line sits from the central core toward the rim. This is radial depth, not a percentage of line capacity.

Arbor and radial depth in this model

The arbor is the spool's central core in this model. Its diameter is fixed at 60% of the rim diameter.

Radial depth measures outward from that core to the rim: 0% places the line at the core; 100% places it at the rim. A 50% setting is halfway across that gap.

Line per handle turn841.4mm≈ 33.1 in

π × 43.2 mm × 6.2 turns

Illustrative result using an assumed core diameter. Open the calculation to see the dimensions and simplifications.

How this is calculated

Arbor is 60% of the rim diameter.
Line sits at 90% of the way from arbor to rim, so the effective diameter is 43.2 mm.
One handle turn = ratio × one rotor or spool turn; each turn recovers one circumference at the effective diameter.
Ignores line stretch, spool taper and how the line beds down.

Two reels with the same ratio recover different lengths because their spools differ in diameter and fill.1 4

Image version This diagram as a picture, to save or print

Diagram of one handle turn beside a spool wrapped with line. Gear ratio counts rotor or spool turns per handle turn; the line recovered also depends on the diameter of the line on the spool.

What does a gear ratio like 6.2:1 mean?

A gear ratio counts turns: with 6.2:1, one full turn of the handle gives 6.2 turns of the rotor on a spinning reel, or of the spool on a baitcaster or conventional reel.1 2 3 4 5 To turn those turns into line, you also need the distance around the line on the spool.

A fuller or wider line pack brings in more line per turn at the same ratio.1 4 Change the diameter in the calculator while the ratio stays the same, and watch line per turn follow it.

High and low gear ratios

With the same spool, a lower ratio brings in less line per handle turn and is usually described as giving more cranking power, while a higher ratio brings in more line per turn.1 3 4 6 7 Where “high speed” begins depends on who is grouping them: one magazine counts spinning reels above about 5:1, and one common grouping for casting reels calls 7:1 and higher fast.4 8 Neither label tells you how much line comes in until you know the spool.

Line depth in the calculator

Line depth is how far the line sits from the core toward the rim. The calculator assumes a core diameter, so its result is a worked example rather than a reading of your reel.

To compare real reels, use the line per turn the maker prints, sometimes given as IPT (inches per turn). Speed would also depend on how fast the handle is turned. A reel’s size number is a separate marking again.

Questions people ask

Is a higher gear ratio faster?: A higher first number means more rotor or spool turns per handle turn. How much line each turn brings in also depends on the spool's diameter and fill, so compare the maker's line-per-turn figure as well.1 2 3 4 5
Why do two reels with the same gear ratio retrieve different amounts of line?: Because line per turn is the spool's effective circumference times the ratio; a bigger or fuller spool recovers more per turn.1 4
Is gear ratio measured the same on spinning and baitcast reels?: The number means the same thing, but on a spinning reel it counts rotor turns around a fixed spool; on a baitcaster it counts spool turns.1 2 3 4 5 9 10 11 12
Is a lower gear ratio more powerful?: With the same spool, a lower ratio brings in less line per handle turn and is usually described as giving more cranking power; a higher ratio brings in more line per turn.1 3 4 6 7
What counts as a high-speed gear ratio?: It depends on who is grouping them. One magazine calls spinning reels above about 5:1 high speed; one common grouping for casting reels is slow at 5:1 or lower, medium around 6:1 and fast at 7:1 and higher.4 8

Sources

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All references 12 in total

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