Size a deck or dock cleat from LOA and/or line diameter: dock line ≈ ⅛ in per 9 ft LOA (min ⅜), then cleat tip-to-tip ≈ 1 in per 1/16 in of line diameter.
Use this when sizing a deck or dock cleat from LOA and/or known line diameter before you order hardware.
Enter LOA (ft) and/or line diameter (in). Line thumb ≈ ⅛″ per 9′ LOA (min ⅜″); cleat tip-to-tip ≈ 1″ per 1/16″ of line (line × 16).
Not a substitute for class rules, mega-yacht hardware standards, or measuring an existing cleat base pattern.
Dock-line diameter follows the same West Marine–style rule as our diameter page: ⅛ in per 9 ft LOA, floor ⅜ in, then rounded up to common rope sizes. Cleat length (tip-to-tip) is about 1 inch of cleat per 1/16 inch of line diameter — e.g. ½ in line → ~8 in cleat.
line_raw_in = max(0.375, LOA_ft × (1/8) ÷ 9) → round up to common size
cleat_in ≈ line_in ÷ (1/16) = line_in × 16
Common cleat bands: ~4–6 in (small craft), 6–8 in, 8–10 in, 10–12 in, 12 in+. Horn cleats only — not a substitute for maker load charts.
Defaults: LOA 30 ft → line raw = max(0.375, 30×0.125/9) = 0.417 → common ½ in class → cleat ≈ 0.5 × 16 = 8.0 in tip-to-tip.
| LOA | Line class | Cleat in |
|---|---|---|
| 18 | ⅜ | 6.0 |
| 27 | ⅜ | 6.0 |
| 30 | ½ | 8.0 |
| 36 | ½ | 8.0 |
| 45 | ⅝ | 10.0 |
Rows follow the page’s round-up-to-common-size logic then cleat = line_in × 16.
Assumptions: open base cleats; LOA drives line when diameter blank; tip-to-tip rule is a retail thumb.
Where it fails: horn cleats vs jam cleats, pop-ups, and through-bolted yacht cleats sized by maker tables.
Not a substitute: planning aid only — match backing plates and fastener WLL.
Yes — if you already know the line, enter diameter to override the LOA thumb.
About one inch of cleat per 1/16 inch of line diameter (½″ line → ~8″ cleat).
That calculator focuses on rope size alone. This page continues to cleat tip-to-tip.
Same thumbs for planning. Exposed docks may want a step larger.
Convert diameter to inches for the cleat rule, or scale carefully — the ×16 rule is inch-based.