Deckwright
Finishing

Deck Stain Calculator

Gallons for the deck floor, railings and stairs, using the coverage printed on your can, plus the cheapest mix of pails and single gallons.

1 Surfaces
ft
ft
ft
0 if not staining
in
sq ft
2 Product
ft²
Labels often list 150–300 ft² on rough or weathered wood and more on smooth new wood. Use the low end for older decks.
Coats
Stain needed
3.6gal
452 ft² × 2 coats
Buy
1×5 gal
4+ single gallons → one 5-gal pail
Deck floor
192ft²
Railings
240ft²
Both faces, as a solid panel
Coverage varies far more by wood than by brand. New, smooth boards absorb little, while weathered or rough-sawn wood can take twice as much. Before you buy, do a test patch and check the label for the coat count and the recoat window.

Railing area counts the railing as a solid panel on both faces, which slightly overestimates baluster railings. Composite and PVC decking is not stained.

Why we ask for your label’s coverage

Coverage claims vary widely from product to product, and even more with the condition of the wood. A new, smooth board absorbs a fraction of what a gray, weathered or rough-sawn board soaks up. So this calculator doesn’t guess. It uses the number on your can, and for older decks we suggest the low end of the label’s range.

Getting the area right

  • Floor: width × depth.
  • Railings: we count each railing as a solid panel on both faces (length × height × 2). Balusters and rails have less surface than a solid panel, but the edges and the overlap from brushing make up much of the difference, and it errs toward having enough.
  • Stairs: add the treads, risers and the outside face of the stringers.
  • Edges: if you will brush stain onto the board edges, tick the option. It adds about 36% of the floor area for 5½″ × 1″ boards.

Questions people ask

How much stain do I need for a 12x16 deck?
The floor is 192 sq ft. At 250 sq ft per gallon, two coats take about 1.5 gallons for the floor alone. Add railings (about 6 sq ft per foot of railing, both faces) and stairs. Use the calculator with your product’s label coverage.
How many square feet does a gallon of deck stain cover?
It depends on the product and the wood. Labels commonly list around 150–300 sq ft per gallon on rough or weathered wood, and more on smooth new wood. Second coats usually go further than the first. Always use the coverage printed on your can.
Should I buy 1-gallon cans or a 5-gallon pail?
If you need four or more gallons, a 5-gallon pail is usually cheaper and keeps the color consistent across the job. For smaller jobs, buy single gallons and box (mix) them together before you start.

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