Deck & Fence Stain Calculator
Estimate stain or sealer for a deck, fence, or other exterior wood project. Enter the total surface area, number of coats, and the coverage printed on your product label.
How this calculator works
Use the area of the wood faces that will actually receive stain. Deck boards, railings, stairs, lattice, and fence rails can add substantial area beyond the footprint. Follow the stain manufacturer’s coverage guidance; rough, weathered, porous, or previously unfinished wood may use more product than a smooth test surface.
required gallons = surface area × coats ÷ label coverage × (1 + allowance ÷ 100) containers to buy = ceil(required gallons)
Worked example
For 400 sq ft, two coats, 250 sq ft per gallon, and a 10% allowance: 400 × 2 ÷ 250 × 1.10 = 3.52 gallons, so plan on 4 one-gallon containers.
Coverage and coats depend on the product
The calculator applies the coverage rate you enter to every coat and adds your chosen allowance before rounding up to whole gallons. Some products recommend one coat, while others call for a second coat or a wet-on-wet application. Check the label for surface preparation, drying time, and recoat instructions before buying or applying.
Test and plan the purchase
A small test patch helps reveal how the wood absorbs the finish and whether your coverage assumption is realistic. This estimate does not account for color changes, application tools, spills, or package sizes smaller than one gallon. Use the manufacturer’s label and your measured surface as the final guide.
Frequently asked questions
How much stain do I need for a deck?
Divide the deck surface area by the product’s stated coverage per gallon, multiply by the number of coats, and add an allowance for absorption and application loss. Include railings, steps, and other faces if they will also be stained.
Should I use one or two coats of deck stain?
Use the coat count and application method specified on the product label. The recommendation varies by stain type, wood condition, and whether the wood has been treated before.
Does fence stain coverage differ from deck stain coverage?
It can. Rough-sawn or weathered fence boards may absorb more product than smooth deck boards. Use the coverage listed for your exact stain and adjust after testing a small area.
Does this estimate include a waste allowance?
Yes. Change the extra allowance field to reflect your own planning margin. The allowance is not a manufacturer specification and does not replace label directions.