Deck Stain Calculator
Find out how many gallons of deck stain or sealer you need - board surface, railings, and multiple coats all included.
How to use this deck stain calculator
Measure the deck surface (length x width). Add railings or steps to include their extra surface area. Pick the coverage of the stain you plan to buy - most cans state the expected sq ft per gallon for smooth wood - and choose one or two coats.
New, bare or rough-sawn wood always needs two coats and drinks stain far faster than a previously sealed deck. When in doubt, buy one extra quart: partial cans are nearly impossible to color-match later because the tinting varies between batches.
Deck stain calculator FAQ
How often should I restain my deck?
Every 2-3 years for semi-transparent stains, and every 3-5 years for solid stains. Water-beading test: if water soaks in rather than beading, it is time to restain.
Should I paint or stain my deck?
Stain penetrates and lets the wood breathe; paint forms a film that can peel on decks. For most outdoor decks, a good semi-transparent or solid stain is the better, lower-maintenance choice.
Can I stain over old stain?
Yes, if the old stain is clean, dry and still bonded. Power-wash, sand lightly, and apply a matching stain. Only strip completely if the old finish is flaking or the wood has grayed badly.