Sizu Home › Calculators › Finish That Lasts
Opens on the book's own fence. Change any number to your own and press Calculate.
Pickets or boards
Rails, gate frame and braces (2x4), and posts
Your finish
Cost per year: the three finishes compared
Enter the parts and press Calculate.
The formula
- Each board: length × 2 × (width + thickness): both faces and both edges
- Rails and braces: length × 2 × (89 + 38) mm; posts above ground: height × 4 × width
- Gallons = coats × area (ft²) ÷ coverage, rounded up. 1 m² = 10.764 ft²
- Cost per year = cost ÷ years it lasts (FPL's range: best case to worst)
The book's worked example, Chapter 9. Route A's 52 pickets, rails, gate and posts come to 20.13 m² (216.66 ft²); two coats at 250 ft² a gallon is 1.73, so 2 gallons. Route B is 43.46 m²: 4 gallons. On Route B, semi-transparent stain costs 22.50 to 45.00 a year, solid stain 16.67 to 41.67, and primer plus two coats of paint 10.50 to 21.00.
New treated wood must dry before it takes a finish: sprinkle water on it, and when the drops soak in instead of beading, it is ready. Lives are FPL ranges for finishes on wood (Wood Handbook, Tables 16-2 and 16-3); a water-repellent preservative alone lasts 1 to 3 years. Prices are illustrative US home-center prices from October 2026, shown without a currency sign; put in your own. Everything stays in your browser: no sign-up, nothing stored.