Boat Ballast Calculator
Find your current ballast ratio and estimate how much additional ballast you would need to reach a target ballast-to-displacement ratio.
Your boat
How much ballast do you want?
What is ballast ratio?
Ballast-to-displacement ratio shows what percentage of the boat's displacement is ballast.
Frequently Asked Questions
How much ballast do I need for my boat?
Enter your boat's displacement, current ballast, and a target ballast-to-displacement ratio. The calculator estimates how much additional ballast would be needed to reach that target.
What is my boat's ballast ratio?
Enter your current ballast and total displacement. The calculator divides ballast by displacement and multiplies by 100 to give your ballast-to-displacement ratio.
How is ballast-to-displacement ratio calculated?
The formula is: Ballast Ratio = (Ballast ÷ Displacement) × 100. For example, 4,000 lb of ballast on a 10,000 lb boat gives a 40% ballast ratio.
How much ballast do I need to reach a 40% ratio?
Enter your boat's displacement, current ballast, and set the target ratio to 40%. The calculator will show the additional ballast required to reach 40%, accounting for the fact that adding ballast also increases displacement.
What happens to displacement when I add ballast?
Adding ballast increases the boat's total displacement. The calculator includes this increase when estimating the additional ballast needed to reach your target ratio.
Does a higher ballast ratio mean a more stable boat?
Not necessarily. Ballast ratio is useful for comparing boats, but it does not describe complete stability. Ballast location, center of gravity, keel geometry, hull shape, loading condition and other factors also affect stability.