Stain Coverage Calculator
Calculate how many gallons of stain you need for decks, fences, and siding by wood type and number of coats.
Based on Smooth wood at 300 sq ft/gal coverage. Cost estimate assumes $30–$60 per gallon for exterior stain.
How It Works
This calculator estimates gallons of stain based on your surface dimensions, wood type, and number of coats. Coverage varies widely depending on how porous the wood is.
Formula: Area = Length × Width (or Height for fences/siding). Gallons = (Area × Coats) ÷ Coverage per Gallon.
Smooth wood covers ~300 sq ft/gal. Rough or weathered wood absorbs more stain and only covers ~150 sq ft/gal. Results are rounded up to full gallons.
Frequently Asked Questions
How much stain do I need for a deck?
Multiply the deck's length by its width to get square footage. A typical 12×16 deck is 192 sq ft. With two coats on smooth wood at 300 sq ft/gal, you would need about 1.3 gallons — so buy 2 gallons. Rough or weathered wood absorbs more stain and requires nearly double.
How many square feet does a gallon of stain cover?
Coverage depends on the wood's porosity. Smooth wood: ~300 sq ft/gal. Cedar or redwood: ~250 sq ft/gal. New pressure-treated: ~200 sq ft/gal. Rough or weathered wood: ~150 sq ft/gal. Always check the manufacturer's label for the specific product.
Do I need one or two coats of stain?
Two coats are recommended for most exterior stain jobs. The first coat penetrates the wood fibers while the second coat builds up color and protection. Semi-transparent stains almost always need two coats; solid stains may be acceptable with one heavy coat on previously stained surfaces.
How much does deck stain cost?
Exterior deck stain costs $30–$60 per gallon depending on brand and type. Semi-transparent oil-based stains run $35–$50, while premium solid stains can reach $50–$60. Budget stains start around $30 per gallon.
What is the best stain for pressure-treated wood?
Use a penetrating semi-transparent stain for pressure-treated lumber. Let new pressure-treated wood dry for 2–4 weeks before staining. Water-based stains work well because the wood's treatment chemicals are water-soluble. Oil-based stains offer deeper penetration but take longer to dry.