Stain Coverage Calculator

Wood stain coverage rates are less predictable than paint because wood porosity varies significantly by species, age, and surface preparation. This calculator gives you a solid starting estimate based on your surface area, coat count, and whether your wood is smooth or rough sawn. Smooth planed wood like sanded deck boards or cedar siding absorbs less stain, giving you roughly 300 square feet of coverage per gallon. Rough sawn lumber, weathered wood, and heavily textured surfaces soak up stain much faster, dropping coverage to around 200 square feet per gallon. Very dry or porous softwoods like pine can be even thirstier on the first coat. Deck staining is the most common DIY stain project. For a typical 12x20 foot deck, the surface area is 240 square feet. With two coats on smooth boards, you need about 1.6 gallons, so buy 2 gallons. If you are also staining the railings, balusters, and stair risers, add 25 to 50 percent more material. Railings have a surprising amount of surface area once you account for all four sides of every baluster. Transparent and semi-transparent stains show the wood grain and require reapplication every 1 to 3 years depending on sun exposure and foot traffic. Solid color stains act more like thin paint, hide the grain, and last 3 to 5 years. The trade-off is maintenance frequency versus natural wood appearance. Always stain a test area first, especially if you are working with an unfamiliar wood species or a new stain brand. Apply stain to a 2x2 foot section and let it dry completely before judging the color. Stain looks dramatically different wet versus dry and can vary from the color chip depending on wood species and porosity. The best conditions for staining are temperatures between 50 and 85 degrees, low humidity, and no rain in the forecast for at least 24 hours. Staining in direct sunlight causes the stain to dry too fast and leads to lap marks and uneven absorption.