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CalcWolf DIY Stain Coverage Calculator
DIY

How Much Stain Do You Need?

Calculate gallons of stain for decks, fences, and furniture based on surface area and wood type.

📅 Updated April 2026 Formula verified 📖 4 min read 🆓 Free · No sign-up

Stain Coverage Rates

Coverage varies significantly by wood condition: Smooth/sealed: 300-400 sq ft per gallon. Weathered/semi-rough: 200-300 sq ft/gal. Rough-sawn: 150-250 sq ft/gal. Rough or porous wood absorbs more stain, requiring more product. A typical 12×16 deck (250 sq ft of surface, including railings) needs 2-3 gallons for two coats.

Application Tips

Always do two coats — one coat often looks blotchy and wears unevenly. Apply when temperature is 50-90°F with no rain expected for 24-48 hours. Sand between coats (lightly with 220 grit) for better adhesion. Use a pump sprayer + back-brush for the fastest, most even application on large decks.

⚡ CalcWolf Insight

The single biggest staining mistake: not cleaning and prepping the surface. Stain applied over dirt, mildew, or old flaking stain will peel within a year. Power wash, let dry completely (48+ hours), and sand smooth before staining. Prep is 70% of the job — the actual staining is the easy part.

Frequently asked questions
How many gallons of stain for a 12x16 deck?
Surface area including railings: approximately 250-300 sq ft. At 250 sq ft/gallon coverage × 2 coats = 2-2.5 gallons. Buy 3 gallons to be safe — you can always use extra for touch-ups or store it for maintenance.
How often should I restain my deck?
Every 2-3 years for horizontal surfaces (deck floor) that get foot traffic and weather exposure. Vertical surfaces (railings, siding) last 3-5 years between coats. If water no longer beads on the surface, it is time to restain.
✓ Math logic verified against primary sources → See our verification process
Kevin Glover
Founder, CalcWolf · GLVTS · Blickr
All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →
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