Deck Stain Calculator

About this calculator

Deck stain quantity is estimated by dividing the deck’s surface area by the product’s coverage rate — typically expressed in square feet per gallon — and multiplying by the number of coats planned: gallons needed = (area × coats) ÷ coverage rate. Coverage rate varies significantly by product type and wood condition: solid-color stains and new, smooth wood cover closer to 250-300 sq ft per gallon, while semi-transparent stains on rough-sawn or weathered, porous wood can drop below 150 sq ft per gallon because the wood soaks up far more product.

DIY homeowners and professional deck contractors use this calculation to buy the right amount before starting a refinishing job, since running short mid-project means an unplanned store run and a visible lap mark where old and new stain meet on a partially dried section, while over-buying wastes money on a product that doesn’t keep well once opened.

Enter your deck’s area, the product’s coverage rate, and the number of coats, and this calculator gives you the gallons and liters you’ll need.