Deck Stain Calculator

About this deck stain calculator

Deck stain quantity is deck area × (1 + railing allowance) × coats ÷ coverage per gallon, rounded up. Coverage is where the answer moves: smooth planed wood gives about 300 sq ft per gallon, standard boards about 250, and rough-sawn or weathered lumber about 200 — because weathered wood drinks stain. Railings and spindles add roughly 20% on top of the floor area (some guides use 15%; railings with many balusters push toward 30%). Our deck stain guide covers prep, coats, and the batch rule.

Two coats is the standard: the first coat soaks in and seals, the second builds the wear layer and the color. A 12 × 14 deck (168 sq ft) needs about 1 gallon for one coat and 2 gallons for two coats with railings at 250 sq ft per gallon — and a 5-gallon bucket covers roughly 1,250 sq ft for one coat, which is enough for most standard decks in a single coat but not for two.

Conditions matter as much as math: stain only when the deck is dry and above 50°F, with no rain for 48 hours, and new pressure-treated wood needs 6–12 months to dry before it takes stain evenly. Stain in the shade — sun dries stain too fast and leaves lap marks — and work in full rows holding a wet edge. And buy in one batch: stain color varies between batches, and a wall finished from two batches can show a line.

How to use

1. Measure your deck length and width in feet (for irregular decks, split into rectangles and add).
2. Choose coats — 2 is standard — and your coverage per gallon by surface (smooth 300, standard 250, rough 200).
3. Add the railing allowance (20% if staining railings and spindles too).
4. Optionally enter the price per gallon, then press Calculate.

Good to know

• Rectangular decks only — multi-level decks and built-in benches/planters should be measured in sections.
• Coverage figures are planning values (300/250/200 sq ft per gallon); the coverage printed on your can governs, and very porous or previously unstained wood can drink more.
• Does not include cleaner, stripper, brightener, sandpaper, or applicators — budget prep supplies separately.