Deck Stain & Sealer Calculator
Calculate gallons of deck stain or sealer needed by deck area, board side count and coats.
The deck stain calculator returns gallons of stain or sealer for any deck refresh or new install. Standard semi-transparent stain covers about 200 sq ft per gallon on smooth wood, 150 sq ft per gallon on rough or weathered wood, 250-300 sq ft per gallon for penetrating oils and clear sealers. For a refresh on an existing deck, count just the top surface plus railings. For a new deck or major restoration, count top + bottom (the bottom face accelerates rot if unfinished). Premium long-life jobs stain all four sides of every board before installation - 3x the material but doubles the deck life.
Explore all our decking calculator tools, or browse the full construction & home improvement diy calculators.
Frequently asked questions
A 10x12 deck (120 sq ft top surface) with a small railing (about 80 sq ft) totals 200 sq ft. Two coats at 200 sq ft per gallon = 2 gallons. For a new deck staining top + bottom (240 sq ft + railing = 320 sq ft) with 2 coats: 3.2 gallons - buy 4 gallons (1 gal + 1 qt extra). Always buy 10-20% more than the calculation - touch-ups years later need exact color match.
Varies dramatically by product type and wood condition. Penetrating oils (Cabot, Penofin, TWP): 250-300 sq ft per gallon on smooth wood. Semi-transparent film-forming stains (most home improvement store brands): 200 sq ft per gallon. Solid-color stains: 150 sq ft per gallon. Rough or weathered wood absorbs 25-50% more than smooth wood. Always read the can - manufacturer specs vary.
Yes if you can - especially for new construction before the deck is built. The bottom of the board exposed to ground moisture absorbs water and rots from below. Pre-staining all four sides doubles deck life vs top-only. For existing decks, stain the bottom is impractical without removing the boards. If you cannot stain the bottom, at least ensure good ventilation under the deck and gravel base to limit ground moisture.
Two coats for new wood or weathered wood undergoing restoration. One coat for a maintenance refresh on a deck that already has good stain coverage. Most semi-transparent stains last 2-4 years; clear sealers last 1-2 years; solid-color stains last 4-7 years before needing recoat. Recoat is just one fresh coat on top of clean, sanded existing finish.
Solid-color stain or deck paint: 5-7 years, hides the wood grain entirely. Semi-transparent stain: 2-4 years, lets grain show through. Clear sealer: 1-2 years, no color but blocks water. Penetrating oil: 2-3 years, soaks into wood rather than forming a film. Film-forming products fail by peeling and need scraping/sanding before recoat; penetrating products fade and recoat without prep.