Trim Stain Paint Calculator

This calculator converts a run of trim into a finish quantity by treating it as a simple one-face surface: Total trim linear ft times Average trim width (in), converted to square feet. Surface area is unaffected by everything downstream of it -- Number of coats, Finish type, Cost per quart ($), whether primer is needed, or the sanding schedule -- since those all describe how the surface gets treated, not how large it is. Coverage varies noticeably by finish type: paint covers about 87 sqft per quart, clear coat about 70, and stain about 62, because stain soaks further into bare wood than a film-forming paint or clear coat does, so the same trim run needs more stain than paint for the same number of coats.

Total Finish Cost adds primer as a separate line, priced at 70% of your chosen finish's cost per quart, on top of the finish itself when Primer needed? is set to yes -- primer is optional and defaults to included, reflecting that bare wood being painted (rather than stained or clear-coated) typically needs a sealing coat first. Sandpaper Sheets scales with both linear footage and the number of sanding grit cycles you specify (e.g., 2 = one pass at 120-grit, one at 220-grit), independent of the finish quantity calculation entirely.