Deck Stain Calculator – How Much Stain Do I Need? | CalcLoft
Find out exactly how many gallons of deck stain you need, including railing extra.
How much deck stain do I need?
Deck stain is measured by the square foot of surface. A 12 × 10 ft deck has 120 sq ft of flooring. Multiply by the boards' visible surface (top + edges ≈ 1.1×) and coats. For 120 sq ft with 2 coats at 250 sq ft/gal: 120 × 1.1 × 2 ÷ 250 = 1.06 → 2 gallons (always round up).
Coverage by deck type
| Surface | Coverage per gallon |
|---|---|
| Smooth, planed wood | 300 sq ft |
| Standard boards | 250 sq ft |
| Rough / weathered | 200 sq ft |
| Railing & spindles | Add 20-30% |
Pro tips
- Stain only when the deck is dry and above 50°F
- New pressure-treated wood needs 6-12 months to dry before staining
- Buy stain in one batch — color varies between batches
Deck stain calculator FAQ
How many gallons of stain for a 12x12 deck?
~144 sq ft × 1.1 × 2 coats ÷ 250 = 1.27 → 2 gallons.
Does a 5-gallon bucket cover a whole deck?
A 5-gal bucket covers about 1250 sq ft (1 coat) — enough for most standard decks with one coat.
Stain or paint for a deck?
Stain soaks in and doesn't peel; paint sits on top and chips. Stain is easier to maintain.
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