Deck Stain Calculator
Estimate how much stain your deck needs.
Default 2
Default 200 per coat
Results update as you type.
How it works
Staining a deck protects the wood and refreshes its look, and this calculator estimates how much stain to buy so you finish the job without a mid-project store run. You enter the deck area in square feet, the number of coats, and the coverage per gallon, and it returns the gallons needed and how many one-gallon cans that is. Coverage depends heavily on the stain type and the wood's condition: transparent and semi-transparent stains often cover 200 to 300 square feet per gallon, while solid stains and rough, dry, or previously unstained boards absorb more and cover less. New or smooth wood usually takes less than weathered wood. Remember to account for railings, stairs, and balusters, which add significant surface area beyond the deck floor; a simple approach is to add roughly the floor area again for a deck with full railings. Most decks get two coats for durable protection, with the first coat soaking in more. Always stain in dry, mild weather and let each coat dry as directed. Enter your deck area, coats, and coverage to see how much stain to buy.
Gallons = area × coats ÷ coverage per gallon
The stain needed equals the deck area times the number of coats, divided by the coverage each gallon provides per coat. Rounding the total gallons up to whole cans tells you how many one-gallon cans to buy. Rough or bare wood lowers coverage, so buy a little extra.
Source:Coating coverage estimate
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter deck area.
- 2
Adjust the options
Adjust number of coats and coverage per gallon if they apply — sensible defaults are already set.
- 3
Read your result
Stain needed updates instantly as you type — no button to press.
Frequently asked questions
How much deck stain do I need?
Multiply the deck area by the number of coats, then divide by the coverage per gallon. A 400-square-foot deck with two coats at 200 square feet per gallon needs 4 gallons. Add extra for railings, stairs, and rough wood, which increase the surface area and absorb more stain than a smooth deck floor.
Does stain type affect coverage?
Yes, significantly. Transparent and semi-transparent stains spread further, often 200 to 300 square feet per gallon, because they soak into the wood. Solid or opaque stains cover less as they build a film on the surface. Always check the product label for its stated coverage and adjust the calculator's rate to match your chosen stain.
Should I include railings in the area?
Absolutely. Railings, balusters, stairs, and fascia add a large amount of surface area that is easy to overlook. For a deck with full railings, a practical rule is to add roughly the floor area again to your total. Skipping this is the main reason people underestimate and run out of stain before finishing.
How many coats of stain does a deck need?
Two coats are typical for good protection and even color, with the first coat absorbing into the wood and the second building durability. Some penetrating stains recommend only one coat, so follow the product instructions. Bare, dry, or previously unstained wood is thirstier and may need more, while smooth or recently stained decks need less.
When is the best time to stain a deck?
Stain on a dry day with mild temperatures, ideally between 50 and 90 degrees Fahrenheit, and no rain expected for 24 to 48 hours. Avoid direct hot sun, which dries stain too fast and causes lap marks. The wood should be clean and dry, so allow a couple of dry days after any rain or washing before staining.