Deck Stain Calculator
Find out how many gallons of stain or sealer your deck needs — accounting for railings, extra coats, and the coverage rate of your product.
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How much stain does a deck need?
Multiply your deck’s length by its width for the floor area, add roughly 3.5 sq ft per linear foot of railing (railings and balusters have a lot of surface), then multiply by the number of coats and divide by your stain’s coverage rate. A 16×12 deck with railings typically needs about 2–3 gallons for two coats.
Why coverage varies so much
Coverage depends on the product and the wood. Semi-transparent stains cover about 200–300 sq ft per gallon, while rough, dry, or previously unstained wood soaks up far more — sometimes only 150 sq ft per gallon on the first coat. Always check the can.
Frequently asked questions
- Do I need two coats?
- Most semi-transparent and solid stains recommend two coats for even color and protection. Clear sealers are often one.
- Does railing really use that much?
- Yes — balusters, posts, and rails have many faces, so a railing run can use as much stain per foot as several square feet of decking.
Plan the rest of your build
- Deck Cost Calculator — total project price.
- Deck Board Calculator — boards and screws.
- Deck Railing & Baluster Calculator — balusters and spacing.