Building a deck? Don't guess the lumber list. Get exact count of boards, joists, and screws for your deck. Works for wood and composite. Waste factor included.
Boards = ⌈Deck Width ÷ (Board Width + Spacing)⌉ | Screws = Boards × Joists × 2The number of boards is calculated by dividing the deck width by the effective board width (board width plus spacing), rounded up. The total screws equal the number of boards multiplied by the number of joists multiplied by 2 screws per intersection.
| Symbol | Meaning |
|---|---|
| Deck Width | Width of the deck perpendicular to board direction |
| Board Width | Actual width of a single deck board in inches |
| Spacing | Gap between boards for drainage |
| Joists | Number of joists across the deck length |
Our calculations are based on established financial and scientific formulas. The following sources inform the default values and methodology used in this calculator:
The waste factor is one of the most important variables in deck material planning. Too little waste means running out of boards mid-project; too much means unnecessary expense. This table shows how different factors affect your recommended waste percentage.
| Deck Layout | Recommended Waste | Board Length Match | Cut Complexity | Total Boards (12x16 deck) |
|---|---|---|---|---|
| Straight / Simple | 8-10% | Perfect match (full boards) | Low — mostly full-width cuts | 34-35 boards |
| Straight / Standard | 10-12% | Good match (standard lengths) | Moderate — some rip cuts | 35-36 boards |
| Diagonal 45° | 12-15% | Partial match | High — angled cuts on every board | 36-38 boards |
| Diagonal + Border | 15-20% | Poor match | Very high — miters and angles | 38-40 boards |
| Herringbone / Pattern | 20-25% | Poor match | Extreme — complex angles | 40-42 boards |
| Composite (hidden fastener) | 10-12% | Good match | Moderate — consistent spacing | 35-36 boards |
A 10% waste factor is the standard recommendation for straight deck layouts with good board length matching. For diagonal layouts, increase to 15%. For complex patterns like herringbone, plan for 20-25% waste. The calculator allows you to adjust this factor from 0-30% to match your specific project. When in doubt, round up — unused boards can be returned, but a mid-project shortage means delays.
The material you choose for your deck affects not just the upfront cost but also long-term maintenance expenses and lifespan. Here is a comprehensive comparison of the most popular decking materials.
| Material | Material Cost/sq ft | Installed Cost/sq ft | Lifespan | Maintenance | 20-Year Total Cost (200 sq ft) |
|---|---|---|---|---|---|
| Pressure-Treated Pine | $2-4 | $8-12 | 10-15 years | High: stain/seal every 1-2 years | $6,000-8,000 |
| Cedar | $4-7 | $12-18 | 15-20 years | Medium: seal every 2-3 years | $7,000-10,000 |
| Redwood | $6-10 | $15-22 | 20-25 years | Medium: seal every 2-3 years | $8,000-12,000 |
| Ipe (Brazilian Hardwood) | $8-15 | $20-30 | 30-40 years | Low: oil every 3-4 years | $9,000-14,000 |
| Composite (Trex, etc.) | $5-10 | $15-25 | 25-30 years | Very Low: wash annually | $7,000-11,000 |
| PVC (Azek, etc.) | $6-12 | $18-28 | 30-50 years | Minimal: wash annually | $8,000-12,000 |
| Aluminum | $10-18 | $22-35 | 50+ years | Minimal: wash annually | $9,000-14,000 |
While pressure-treated pine has the lowest upfront cost ($8-12/sq ft installed), its 20-year total cost is similar to composite decking ($7,000-8,000 vs $7,000-11,000) because of recurring maintenance expenses. For the best long-term value, composite decking offers the sweet spot — moderate upfront cost, minimal maintenance, and 25-30 year lifespan. PVC is ideal for wet areas (around pools, in rainy climates) as it is completely waterproof. Use this deck material calculator to estimate material quantities for your specific deck size.
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Rates verified 2026-10-09 · Sourced from official seller fee schedules