Deck Stain Calculator: How Much Stain Do I Need
Work out how much stain or sealer a deck needs. Enter the deck length and width, the number of coats and any railing, and get the gallons to buy.
How to estimate deck stain
- Enter the deck length and width in feet.
- Set the number of coats, your stain coverage, and the railing length.
- Read off the total surface area and the gallons of stain to buy.
Examples
12 by 16 ft deck, 2 coats, 40 ft railing
Length 12, width 16, 2 coats, railing 40 ft
624 sq ft to cover, 4 gallons
Frequently asked questions
How much stain do I need for a deck?
Multiply the deck length by width for the floor area, add about 3 square feet per linear foot of railing, multiply by the number of coats, then divide by the coverage on the can. A gallon usually covers around 200 square feet per coat.
How much area does a gallon of deck stain cover?
Roughly 150 to 350 square feet per coat depending on the product and how thirsty the wood is. New or rough boards soak up more, so coverage drops. The calculator uses 200 square feet per gallon by default.
How many coats of stain does a deck need?
Most deck stains call for two coats for an even, durable finish. Some penetrating oils are a single heavy coat, so always follow the label, which is why coats is adjustable here.
Why count the railing separately?
Railings have a top rail, two faces and many balusters, so they add a surprising amount of surface. Estimating about 3 square feet per linear foot of railing captures all of it.
Should I buy a little extra stain?
Yes. Buy slightly more than the estimate so you can keep a wet edge, cover thirsty spots, and have matching stain for touch ups. Stain is sold in whole gallons, so the result rounds up.
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