Measure area, choose coats, then get gallons fast. Factor rails, stairs, and wood porosity too. Export results anytime for tidy jobsite records today always.
| Scenario | Deck | Rails | Stairs | Coats | Type | Coverage | Waste | Estimated stain |
|---|---|---|---|---|---|---|---|---|
| Typical raised deck | 20 ft × 12 ft | 40 ft × 3 ft × 2 faces | Off | 2 | Semi | 225 ft²/gal | 10% | ~3.25 gal (rounded) |
| Small entry deck | 10 ft × 8 ft | 20 ft × 3 ft × 1 face | 5 steps | 1 | Transparent | 275 ft²/gal | 8% | ~1.25 gal (rounded) |
| Weathered boards | 260 ft² custom | Off | Off | 2 | Solid | 175 ft²/gal | 12% | ~3.75 gal (rounded) |
The calculator converts all areas to square feet internally, then estimates volume using:
Accurate stain planning starts with a reliable area takeoff. Measure the deck walking surface, then add railing faces and stair treads and risers if they will be stained. For irregular layouts, break the plan into rectangles or use a premeasured total area. Record units consistently, because small input errors multiply across coats and waste allowances. Include fascia boards only if you plan to coat them.
Coverage rates on product labels are laboratory numbers that assume smooth, dry lumber and ideal application. Weathered boards, wide pores, and end grain absorb more material, lowering practical coverage. This calculator applies texture and porosity factors to reflect field conditions. If you know your stain’s true spread rate from past jobs, override the default to match your product and method. Sprayer use may raise waste, especially in breezy conditions.
Coat count changes volume linearly, but the first coat typically consumes the most. New or heavily sanded decks can require a generous first pass, while the second coat often levels color and seals missed spots. Plan for overlap at board joints, roller loading, and brush work around fasteners. A realistic waste percentage reduces midproject shortages and color batch mismatch. Dark colors often reveal missed spots, so inspect carefully.
Purchase rounding is as important as the exact estimate. Retail packaging usually comes in one-gallon cans and five-gallon pails, so rounding up to quarter-gallon increments helps map estimates to real containers. Use the packaging suggestion to minimize leftovers while still protecting the schedule. Keep one extra small can for touchups, especially on high-traffic edges and steps. Store sealed containers upside down to reduce skinning.
Application quality affects both appearance and consumption. Clean and dry the surface, then follow temperature and humidity limits to avoid flashing and lap marks. Maintain a wet edge, back-brush into board texture, and avoid overloading grooves. Track what you used per coat and update your override coverage for the next maintenance cycle to improve budgeting. Document batch codes to maintain color across sections.
Only include it if you will actually stain it. Most maintenance work covers top surfaces, exposed edges, rails, and stair parts. Undersides are often left unfinished or treated separately for moisture control.
Split the plan into simple rectangles, add their areas, then enter a custom total. Alternatively, measure each section’s length and width and sum them. This approach reduces mistakes compared with rough guessing.
Use the lower coverage number for rough, weathered, or thirsty wood. Use the higher number for smooth boards and careful application. If you have job history, override with your proven rate.
Field surfaces rarely match lab conditions. Rough grain, cracks, and dry fibers absorb stain and reduce spread rate. The factors adjust the estimate so purchase quantities better match real consumption.
A small reserve is helpful for edges, steps, and future repairs. The waste percentage and quarter-gallon rounding often create a practical buffer. For large decks, consider one extra one-gallon can.
Yes. Enter the coverage rate from your exact product and adjust factors for surface condition. Application tools and drying time differ by chemistry, but area, coats, and coverage still govern quantity.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.