Deck care · Updated November 3, 2026
Deck stain coverage calculator
Estimate deck stain from the surfaces you measure, planned coats, and first- and later-coat coverage on your selected product label.
Enter the total area of the surfaces you plan to stain, the planned coat count, and coverage copied from the selected product's current label or data sheet. First- and later-coat coverage can differ; this calculator does not supply a default product yield.
Enter positive values and calculate.
Measure the faces you will coat: deck boards, railings, stairs, fascia, ends or other surfaces as applicable. A deck footprint alone omits vertical and edge surfaces. Avoid counting any face twice. Actual coverage varies by product, wood condition, surface shape and application; verify the current label and prepare the surface as directed.
How the estimate works
First-coat gallons = measured area ÷ first-coat coverage. Later-coat gallons = measured area × (coat count − 1) ÷ later-coat coverage. The calculator adds those amounts and reports the estimate before rounding to a package size. It uses the same entered area for each coat and does not add a waste allowance.
Coverage is product-specific. BEHR's Semi-Transparent Waterproofing Stain & Sealer data sheet lists separate rates for its first and second coats and says two thin coats are required. BEHR's DECKplus Solid Color data sheet also lists separate rates, with two thin coats recommended. These examples illustrate label differences; they are not universal yields. Copy coverage and coat instructions from the exact product you will use.
For preparation and application steps, see BEHR's How to Stain a Deck. That guide covers its featured semi-transparent stain. Follow the instructions for your selected product and substrate; wood, composites, weathering, board edges and railings can require different preparation or coverage assumptions.
How it works
Measure the actual surfaces you plan to coat, including any railings, stairs, exposed ends or board sides you want in the estimate. Enter the coat count and the selected stain's labeled coverage for the first and later coats. The result estimates gallons before package rounding.
Good to know
Quick answer: how much deck stain should I estimate?
For the first coat, divide measured stainable area by the selected product's first-coat coverage. For each later coat, divide that area by the product's later-coat coverage. Add those gallon amounts. Reviewed November 3, 2026. Use the current label for the exact stain and surface: BEHR data sheets show that first- and second-coat spread rates can differ, and actual coverage varies with surface condition and application.
What area should I measure?
Enter the surfaces you actually plan to coat. A deck's plan-view floor area does not include railings, stairs, fascia, board edges or underside surfaces. Measure those separately if they will be stained, and avoid counting the same face twice.
Why are first- and later-coat coverage separate?
The selected product label may give different spread rates by coat. For example, BEHR's cited Semi-Transparent Waterproofing Stain & Sealer data sheet lists 250–300 sq ft per gallon for coat one and 500–600 sq ft per gallon for coat two, and specifies two thin coats. These figures apply to that product sheet; enter the values for the stain you selected.
Does the calculator tell me how many coats to apply?
No. Follow the current label and project instructions for the exact product and surface. BEHR's deck guide discusses a second coat for its featured semi-transparent stain, but coat requirements are not universal.
Why might actual use differ from the estimate?
Coverage depends on the product, wood condition and porosity, surface shape and application. This area calculation does not account for spills, leftover product or every textured or hard-to-reach surface. Check the label and measure all faces you intend to coat; the result is not a purchase guarantee.
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