Deck Stain Calculator
Gallons of deck stain by deck size and coats.
Stain to buy
2 gal
Deck area
192 sq ft
Stain (2 coats)
1.5 gallonsbuy 2 gal
Coverage
250 sq ft / gallonper coat on bare decking
Stain cost (est.)
$70~$35/gal
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Staining or sealing protects a deck from UV and water — the two things that gray and split bare wood. The single biggest factor in how long it lasts is surface prep: clean, dry wood drinks stain and holds it for years.
DifficultyBeginner
TimeA weekend — clean and dry one day, stain the next
SkillsNo special skills; just dry weather and patience between coats
Tools you'll need
- Stiff brush and deck cleaner/brightener
- Pump sprayer or pad applicator
- Stain brush for railings
- Painter's tape and drop cloths
- Moisture meter (optional but helpful)
Step by step
- Clean the deckSweep, then wash with deck cleaner to strip dirt, mildew, and old finish. A brightener restores grayed wood.
- Let it dry fullyWood must be dry — ideally under ~15% moisture and after 24–48 hours of dry weather. Staining wet wood is the top reason finishes peel.
- Check the forecastYou want a dry, mild window: no rain for 24–48 hours and out of direct hot sun, which flash-dries stain before it penetrates.
- Apply thin, even coatsWork a few boards at a time end-to-end to keep a wet edge. Back-brush to push stain into the wood and avoid puddles.
- Second coat if neededSemi-transparent stains often want two thin coats; follow the can. Wipe any excess that hasn't soaked in.
Common mistakes
Staining wood that's still wet
Wait for dry wood and dry weather, or the finish won't penetrate and will peel.
Applying too thick
Stain isn't paint — thick coats sit on top, stay tacky, and peel. Thin coats that soak in last longest.
Staining new pressure-treated wood too soon
Let new PT lumber dry out (weeks to months) until water soaks in rather than beads, then stain.
Safety
- Ventilate and follow the stain's safety notes.
- Oil-soaked rags can spontaneously combust — dry them flat outdoors before disposal.
Frequently asked questions
How much deck stain do I need?
Enter your deck size and coats above — the calculator returns gallons at ~250 sq ft per gallon on bare decking.
How long should wood dry before staining?
At least 24–48 hours of dry weather after cleaning; new pressure-treated lumber may need weeks to months.
Stain or seal?
Clear sealers protect against water; semi-transparent stains add UV protection and color, which makes them last longer outdoors.
Next steps for this project
Sources & references
- Follow the stain manufacturer's prep and coverage instructions