Deck Stain Calculator
Enter your deck dimensions, how many coats you're applying and the coverage rate on your stain's label. The calculator returns the total area, gallons of stain required, and estimated cost — rounding up to whole cans, since you can't buy a fraction of a gallon.
Common sizes
Jump to a pre-filled estimate:
How it works
Deck area = length × width, with an optional 15% uplift for railings and balusters, which soak up more stain than flat boards. Multiply by the number of coats, divide by the coverage rate on the can, and round up to whole gallons.
The formula
Gallons = (Length × Width × railings-factor × Coats) ÷ Coverage per gallon. Most deck stains cover 150–350 sq ft per gallon; rough or thirsty wood is at the lower end.
Worked examples
| Example | Result |
|---|---|
| 16×12 deck, 2 coats | A common deck size: about 2.2 gallons with railings included. |
| 20×20 deck, 1 coat | Larger deck, single maintenance coat: about 1.6 gallons. |
Frequently asked questions
How much stain do I need for a deck?
As a rule of thumb, one gallon covers 150–350 square feet per coat depending on the product and how absorbent the wood is. New or rough wood drinks more stain than previously-sealed boards.
Do I need to include railings?
Yes — railings, balusters and stairs add roughly 10–20% to the surface area because they're stained on multiple faces. This tool adds 15% when you include them.
How many coats of deck stain?
Most semi-transparent and solid stains are applied in two coats on bare wood; a single maintenance coat is often enough when re-staining an existing finish.
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Method reviewed by The editorial team. See our methodology for sources and assumptions.