Marine Sail Area / Displacement Ratio Calculator
Calculate the conventional sail area to displacement index from sail area in m² and displacement mass in kg.
A QUICK WALKTHROUGH
How to use this tool
- Enter positive sail area in m².
- Enter positive displacement mass in kg.
- Calculate the numeric index, then copy or download the report.
Formula and units
SAft² = SAm² ÷ 0.3048²; Dlb = Dkg ÷ 0.45359237. Index = SAft² ÷ (Dlb/64)^(2/3).
Scope
The value 64 is a fixed normalisation convention for this index, not your actual water density. This tool supplies no performance thresholds, sail-condition advice, stability or safety assessment.
Local processing
Inputs stay in your browser. The report includes inputs, formulas and scope.
GOOD TO KNOW
Common questions
Does this index classify performance or sailing conditions?
No. It returns only the conventional numeric index and provides no categories or recommendations.