How Many Gallons of Deck Stain for 400 Square Feet?

For a 400 sq ft deck floor (e.g., 20×20 ft), one gallon of penetrating semi-transparent oil stain covers 200 to 250 sq ft on weathered wood. Therefore, you need 2 gallons for the floor. If staining perimeter railings, balusters, and stair steps, add an additional 2 to 3 gallons (total 4 to 5 gallons for the entire deck project).

Worker staining an outdoor cedar wood deck floor with rich natural cedar penetrating oil stain

Published 2026-03-01 · Updated 2026-03-01 · 8 min read

Deck Railing and Spindle Surface Area Rule of Thumb

Homeowners routinely forget that deck railings contain tremendous surface area. A standard 36-inch high railing with 2×2 balusters spaced 4 inches on-center has approximately 1.5 to 2.0 square feet of wood surface per linear foot of railing. A 50-linear-foot perimeter railing adds 75 to 100 sq ft of staining area.

Worked Example: 400 Sq Ft Deck + 40 Linear Ft Railing + 4 Steps

Staining a pressure-treated pine deck with 2 coats of semi-transparent penetrating stain.

Order 4 gallons of semi-transparent deck stain.

How often should a wood deck be restained?

Clear sealers require annual application, semi-transparent stains last 2 to 3 years, and solid color deck stains last 4 to 5 years on horizontal walking boards.

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