🎨 Wet Film Thickness Calculator
Convert between wet film and dry film thickness using the paint's volume solids — with optional thinning — so you can check the coating with a comb gauge and build the specified dry film on the hull.
🎨 Convert WFT ↔ DFT
What is a Wet Film Thickness Calculator?
Marine coatings are specified by their dry film thickness, but the only thing you can measure while painting is the wet film. This tool bridges the two: enter a target DFT and the paint's volume solids and it tells you the wet film to lay down, or enter a measured WFT to see the dry film you'll be left with.
Hitting the right film thickness is what makes a coating perform — too thin and it fails early, too thick and it can sag, wrinkle, or waste paint. Use this alongside a wet film comb gauge to apply antifouling, primer, and topcoats to spec every time.
❓ Frequently Asked Questions
What's the difference between wet film and dry film thickness?
Wet film thickness (WFT) is how thick the coating is the instant you apply it, while it still contains solvent. Dry film thickness (DFT) is what's left once the solvent evaporates and the coating cures. Because the solvent leaves, DFT is always less than WFT — the ratio is set by the paint's volume solids.
How do I convert DFT to WFT?
Divide the target dry film thickness by the volume solids expressed as a fraction: WFT = DFT ÷ (volume solids % ÷ 100). For example, a 100-micron DFT with 50% volume solids needs a 200-micron wet film. This calculator does the maths both ways and accounts for thinning.
Why does thinning change the wet film I need?
Thinning adds solvent, which lowers the volume solids of the paint as applied. Since more of the wet film is now solvent that will evaporate, you have to lay on a thicker wet film to be left with the same dry film. Enter the thinning percentage and the calculator raises the required WFT accordingly.
How do I measure wet film thickness on the hull?
Use a wet film comb (thickness) gauge — a stepped metal or plastic comb you press into the fresh coating. The reading is the gap between the last tooth that's wetted and the first that's clean. Check it as you apply so you can add or spread paint to hit the specified thickness before it starts to cure.