Deck Stain Calculator: Gallons for Floor & Railing

Stain being brushed onto railing balusters

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 deck

Deck floor

Deck lengthft Deck widthft

Railing

Don't know your baluster count? The railing calculator counts it from the railing length. Leave the railing at 0 for a deck without one.

Railing lengthft Balusters Railing posts Baluster heightin Post heightin

Stain

Wood Stain type Coats

Optional

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

Transparent deck stain per gallon USD Typical $25–$55 Semi-transparent deck stain per gallon USD Typical $30–$60 Solid deck stain per gallon USD Typical $30–$65

Add an installed cost estimate
Adds a labor band of $1–$3 per square foot

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.

Tools for the job

What makes this job easier

Tools and materials that suit this kind of job. These are affiliate links: if you buy through one, Renovimo may earn a commission at no extra cost to you. It never changes the figures on this page.

Tilswall Cordless paint sprayer, 20 V No cord to drag along a fence line or across a deck; runs on DeWalt 20 V batteries (not included). Check price

Garvee Airless paint sprayer, 2900 PSI Coats whole rooms, fences and siding far faster than a roller. Check price

Garvee Cordless pressure washer Cleans a deck or patio before stain or sealer goes on. Check price

Garvee 6 in random orbital sander Smooths stair treads, rails and trim before finishing. Check price

Garvee Pro paint roller kit, 32 pieces 9 in and 4 in rollers on a telescoping pole, for walls and ceilings without a ladder. Check price

Garvee Clear PVC tarp, 8 × 12 ft Covers a fresh slab to cure, or keeps a lumber or drywall stack dry. Check price

Not the tool you were after? Browse the whole range at Tilswall or Garvee — the stores these picks come from.

A brush laying finish along a wooden board

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 Amazon: Opens the grain so the stain goes in evenly; Check the label
Stain pad and pole Amazon: For the floor, working two or three boards at a time; 1
Brushes Amazon: For balusters, rails and the ends of boards; 2
Drop cloths and tape Amazon: Siding, the house wall and anything planted below; —

As an Amazon Associate I earn from qualifying purchases.

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.

floor = length × width
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.