Deck Stain Calculator
How much stain a deck takes, by stain type and coats — gallons and quarts to buy, with a railing allowance for decks with balusters and rails.
Stain coverage, by what is in the can
Deck stain coverage is set by how much solid the product leaves behind. A clear toner is nearly all carrier and drinks deep into the wood — around 225 sq ft per gallon per coat on smooth decking. Each step toward a solid color leaves more film on the surface and covers more ground: semi-transparent about 250, semi-solid about 300, and a solid color stain, which behaves like a paint, about 350. The calculator prices your deck at the rate for the stain you pick, across the coats you plan, and adds a 30% area allowance when railings join the job — balusters are small surfaces that add up to a lot of brushing.
Gallons = deck area (× 1.3 with railings) × coats ÷ coverage rate · bought as whole gallons + quarts
Example: a 16 × 12 ft deck is 192 sq ft. Two coats of semi-transparent stain = 384 sq ft of coating to lay down; at 250 sq ft per gallon that is 1.54 gallons — buy 1 gallon + 3 quarts.
Weathered, rough-sawn or thirsty old wood drinks more than the printed rate — the first coat on bare, dry decking can take a third more than the second. That is the quiet virtue of the gallons-plus-quarts answer: the last quart is bought only if the deck actually drinks it. The same method covers a fence: measure one face of the fence run as the "deck area," choose floor only, and note board fences with gaps drink a little more per square foot than a deck does.
Frequently asked questions
How many coats of deck stain should I apply?
Most stains are a two-coat system on bare wood, applied wet-on-wet or after the first coat tints but before it fully cures — the can's label rules. A sound existing finish being refreshed often needs only one. More coats than the system wants can leave a film that peels, especially with solid stains.
Can I stain a new pressure-treated deck right away?
Not while it is still wet with treatment — the wood needs to dry until water sprinkled on it soaks in rather than beading, which can take from a few weeks to a season depending on climate. Stain over damp treated lumber traps moisture and fails early.
What is the difference between semi-transparent and solid stain?
Semi-transparent lets wood grain show through its color and wears by fading, so recoating is easy. Solid stain hides the grain like paint, lasts longer per coat, but wears by peeling on horizontal surfaces and is a bigger job to renew. Deck floors usually live happier in semi-transparent; fences and railings carry solids well.
How long does deck stain last?
On a horizontal deck floor, expect 2–3 years from semi-transparent and 3–5 from a solid before recoating; vertical surfaces like railings and fences go noticeably longer, since weather and foot traffic are what wear a coating. Sun exposure halves or doubles those figures either way.
CalcCoverage