Deck stain calculator
Deck stain calculator
How much stain a deck takes is mostly a question about the railing. Every post, rail and baluster has four faces, and together they often add up to more surface than the floor. Enter both and get the gallons for each.
Enter your deckOptional
What will it cost?
Every material the calculator worked out gets its own price. Each field starts at a typical US figure so you have something to work from — change any of them to what your own supplier charges.
These prices are approximate. They are national US retail figures, and what you actually pay varies with your region, your supplier, the season and how much you buy at once. Treat them as a starting point, not a quote — always price the job from your own supplier's current figures before you order.
Your prices
More in this series
The rest of the deck
A deck is boards, frame, stairs, railing and finish. The sizes you have entered here carry across to the rest.
- Deck Material Calculator Deck boards by length, joists, beam, posts, hangers and screws or hidden clips
- Deck Stair Stringer Calculator Stringers, treads, risers and the cut that keeps every step even
- Deck Railing and Post Spacing Calculator Railing posts, balusters under the 4 in rule, rails, brackets and screws
- Deck Footing Sizes and Spacing Form tube sizes, pad size by load and soil, and frost depth
- Deck Joist and Beam Span Tables Joist spans by species, size and spacing, beam spans, cantilevers and ledger fasteners
- Deck Board Sizes and Lengths Nominal and actual decking sizes, stock lengths, coverage and joist spacing
Based on your result
What you'll need
Buy it all from one batch, or box the cans together before you start — tints drift between batches, and a railing shows it.
- Deck stain
- Floor and railing, all coats
- Calculate above
- Deck cleaner or brightener
- Opens the grain so the stain goes in evenly
- Check the label
- Stain pad and pole
- For the floor, working two or three boards at a time
- 1
- Brushes
- For balusters, rails and the ends of boards
- 2
- Drop cloths and tape
- Siding, the house wall and anything planted below
- —
The maths
How this deck stain calculator works
The floor is length times width. The railing is not its length: it is every face of every piece in it. A 2 × 2 baluster has four faces, a 34 in baluster is nearly 1.5 square feet of wood, and a 6 ft section holds a dozen of them. Stain coverage is the square feet a gallon covers per coat, and weathered wood soaks up about half as much again as new.
rails = railing ft × (14 in + 10 in) ÷ 12
balusters = count × 6 in × height ÷ 144
posts = count × 14 in × height ÷ 144
gallons = ⌈ area × coats ÷ coverage ⌉
- 01
Measure the floor
Length times width. If the stairs are being stained too, add their treads to the floor area.
- 02
Unfold the railing
The top rail is a 2 × 6 with four faces, 14 in round; the bottom rail a 2 × 4, 10 in round; each baluster 6 in round; each post 14 in round. Their round times their length is the wood to stain.
- 03
Pick the coverage
Makers quote wide ranges — roughly 200 to 500 sq ft a gallon on new, smooth wood and 150 to 300 on weathered wood, depending on the product. The calculator plans at 300 and 200, toward the cautious end, because real decks rarely reach the best figure on the can.
- 04
Multiply by coats
Most semi-transparent and solid stains want two coats; a transparent toner often only one. Round up to whole gallons.
Good to know
Deck stain questions, answered
The floor is 192 sq ft: at 300 sq ft a gallon on new wood, two coats take 1.28 gallons. Add a railing on three sides — 40 ft with 81 balusters and 8 posts — and that is another 227 sq ft, 1.52 gallons. About 3 gallons for the whole deck, of which the railing is more than half.
Because it is all edges. Every baluster has four faces and there are about two to a foot of railing; add two rails with four faces each and the posts, and a 40 ft railing carries more wood surface than a 12 × 16 floor.
Two for most semi-transparent and solid stains, applied the same day while the first is still receptive — check the can. A transparent toner is often a single coat. Second coats usually go further than first ones.
Yes. Grey, rough wood soaks up far more than new boards: labels quote roughly 150 to 300 sq ft a gallon on weathered wood against 200 to 500 on new, and the calculator plans at 200 and 300. Cleaning it first helps the stain go on evenly, but it still takes more.
Transparent shows the most grain and wears fastest; semi-transparent colours the wood but lets the grain through; solid covers like paint and lasts longest on horizontal boards, but peels rather than fades when it goes.