Enter your deck dimensions, railing length, and stair count to get the exact number of gallons needed. Adjusts for stain type and wood condition. Free — no signup required.
| Deck Size | Stain | Condition | Gallons |
|---|---|---|---|
| 200 sq ft | Solid | New | 1 |
| 200 sq ft | Solid | Weathered | 1 |
| 400 sq ft | Solid | New | 2 |
| 400 sq ft | Solid | Weathered | 2.5 |
| 600 sq ft | Semi | New | 2 |
| 600 sq ft | Semi | Weathered | 2.5 |
A 16×12 ft deck (192 sq ft) with 44 linear feet of 42-inch railing and 8 stair treads, using semi-transparent stain on weathered wood with 2 coats: railing area = 44 × 3.5 × 2 = 308 sq ft; stair area = 8 × 3 × 2 = 48 sq ft; total = (192 + 308 + 48) × 2 = 1,096 sq ft. At 280 sq ft/gal, you need 1,096 ÷ 280 ≈ 3.9 gallons — buy 4 gallons.
For a 400 sq ft deck with semi-transparent stain on new wood with 2 coats: 400 × 2 / 350 ≈ 2.3 gallons. Buy 3 gallons to be safe.
Semi-transparent shows the wood grain and suits newer, good-condition wood. Solid hides grain and imperfections — better for weathered or damaged decks.
Oil-based stains: every 2–3 years. Water-based: every 2–4 years. Decks in full sun or wet climates need more frequent maintenance.
Most stain coverage rates are for flat horizontal surfaces. Railings absorb significantly more due to vertical surfaces, end grain, and balusters. Always calculate railings separately.
The coverage rates already account for some absorption. For rough or weathered wood, the 'rough' condition setting reduces coverage automatically. Buy one extra quart as insurance.
Typical Results
💡 Buy one extra quart beyond your calculated amount — running short mid-project causes lap marks where wet and dry stain meet.
Common Mistakes