How to Calculate Deck Stain
Measure your deck floor area (length × width) and add the railing surface area. For railings, estimate 3 square feet per linear foot to account for balusters, top rail, and posts. One gallon of deck stain covers approximately 150–250 square feet depending on wood porosity and stain type. Semi-transparent stains cover more area than solid stains.
When to Restain Your Deck
Most decks need restaining every 2–3 years. To test, sprinkle water on the deck — if it beads up, the stain is still effective. If it soaks in, it's time to restain. The best time to stain is during mild weather (50–80°F) with no rain forecast for 24–48 hours.