🛥️ Antifouling Paint Calculator
Enter your hull area, the number of coats, the paint's coverage, and the price per litre to see how many litres you need, how many whole tins to buy, and what the antifouling will cost.
🛥️ Size Your Antifouling Order
What is an Antifouling Paint Calculator?
It takes the guesswork out of ordering bottom paint. Punch in the wetted hull area, how many coats you plan to apply, the coverage from the tin, and the price, and it returns the litres needed, the whole tins to buy, and the total cost — so you turn up to the yard with exactly the right amount.
Antifouling protects the hull below the waterline from slime, weed, and barnacles that slow the boat and burn fuel. Use this to plan a bottom job, compare products by cost per season, and avoid the classic trap of running out of paint halfway up the topsides.
❓ Frequently Asked Questions
How much antifouling paint do I need?
Multiply the hull's wetted area by the number of coats, then divide by the paint's coverage in square metres per litre. This calculator does that and rounds up to whole tins, since you can't buy a partial can. If you don't know your wetted area yet, work it out first with a hull area calculator.
How many coats of antifouling should I apply?
Two coats is typical for a season, with a third on high-wear areas like the waterline, leading edges, and the rudder where fouling and abrasion are worst. Follow the paint manufacturer's data sheet — some products specify a minimum dry film thickness that dictates the coat count.
What coverage figure should I enter?
Use the practical coverage from the tin, usually around 8–12 m² per litre for antifouling depending on the product and how it's applied. The theoretical figure on the data sheet assumes perfect application; real-world coverage is lower once you account for the surface, the roller, and losses, so the practical number gives a safer estimate.
Should I buy extra paint?
Yes — a little. Rounding up to whole tins usually leaves some spare, but buy an extra part-tin if your area estimate is rough, the hull is rough or porous, or you want touch-up paint that matches. Antifouling has a shelf life, so don't massively overbuy for a single season.