Lumber Calculator
Enter lumber dimensions, length, and quantity to calculate board feet and estimate cost. Supports common lumber sizes and helps plan decking, framing, and woodworking projects.
Lumber pricing is one of the most variable construction costs, fluctuating ~30-50% between years and ~10-20% seasonally. Knowing your project's exact lumber needs in advance — whether for framing, decking, fencing, or DIY furniture — prevents the panic mid-project when prices have spiked or items go out of stock. This calculator handles the common case: lumber dimensions and quantity converted to board feet (the standard hardwood pricing unit) and total cost.
The calculator multiplies your inputs to give total board feet and dollars. For framing lumber (2×4s, 2×6s, etc.), it works just as well as the dedicated board-foot calculator. The math is identical: board feet = (thickness × width × length-in-feet) / 12. A typical residential framing project uses several hundred to several thousand board feet of lumber.
Lumber comes in many forms: rough-sawn (raw from the sawmill), surfaced (planed for finished look), pressure-treated (rot-resistant for outdoor use), kiln-dried (stable for indoor use), and various grades from premium clear to construction-grade. Choose based on the application and budget. For framing: standard #2 SPF (Spruce-Pine-Fir) #2 grade. For outdoor: pressure-treated southern yellow pine. For visible furniture: kiln-dried hardwood (oak, walnut, etc.) in FAS grade.
Inputs
Nominal thickness (e.g., 2 for a 2x4)
Results
Total Board Feet
53.33
Total Cost
$266.67
Cost per Board
$26.67
Linear Feet
80 ft
Lumber Breakdown
| Detail | Value |
|---|---|
| Board Size | 2" x 4" x 8' |
| Board Feet / Piece | 5.33 |
| Quantity | 10 |
| Total Board Feet | 53.33 |
| Total Linear Feet | 80 ft |
| Cost per Board | $26.67 |
| Total Cost | $266.67 |
Formula
How to use this calculator
- Enter thickness in inches (1 for 1×, 2 for 2×, etc.).
- Enter width in inches.
- Enter length in feet.
- Enter quantity of boards.
- Enter price per board foot.
- Calculator returns total board feet and cost.
Worked examples
Framing for a small room addition
**Scenario:** 10 × 12 ft addition with 8 ft ceilings. Need: 20 wall studs (2×6×8), 10 floor joists (2×10×12), 4 ceiling joists (2×8×12). **Calculation:** Wall studs: 20 × 7.33 BF = 147 BF. Floor joists: 10 × 20 BF = 200 BF. Ceiling joists: 4 × 16 BF = 64 BF. Plus headers, blocking, double plates: ~150 BF. Total: ~561 BF. At $0.85/BF for #2 SPF: $477 in framing. **Result:** ~$500 in framing lumber for a small addition. Plus sheathing, fasteners, sill plate, etc. (~$300-400): total framing materials ~$900-1000. Add insulation, drywall, finishes for full room cost of ~$8000-15000.
Deck project breakdown
**Scenario:** 16 × 20 ft pressure-treated deck. Need: 12 4×4 posts × 10 ft, 4 2×10 beams × 16 ft, 18 2×10 joists × 16 ft, 90 2×6 decking boards × 16 ft, plus railing. **Calculation:** Posts: 12 × 11.67 BF = 140 BF. Beams: 4 × 26.67 BF = 107 BF. Joists: 18 × 26.67 BF = 480 BF. Decking: 90 × 14.67 BF = 1320 BF. Railing (pickets, rails, posts): ~200 BF. Total: ~2247 BF. At $1.50/BF for pressure-treated: $3370 in lumber. Plus joist hangers, screws, brackets, footings: ~$500. Total materials: ~$3900. **Result:** ~$3900 in lumber for typical pressure-treated deck. Pro install adds $4000-7000 labor. DIY save labor; budget 3-5 weekends for first-time deck build.
Fence material order
**Scenario:** 100 lf of 6-ft cedar privacy fence. Need: 13 4×4 cedar posts × 8 ft, 39 2×4 cedar rails × 8 ft, 343 1×4 cedar pickets × 6 ft. **Calculation:** Posts: 13 × 9.33 BF = 121 BF. Rails: 39 × 5.33 BF = 208 BF. Pickets: 343 × 1.75 BF = 600 BF. Total: ~929 BF. At $5/BF for cedar: $4645 in lumber. Plus concrete, fasteners, gate kit, stain: ~$700. Total materials: ~$5400. **Result:** ~$5400 for cedar fence materials. Pro install: $1500-3000 additional. Cedar lasts longer than pine and weathers attractively to silver gray. Pressure-treated southern pine would cost ~$2700 instead — half the cedar cost.
When to use this calculator
**Use the lumber calculator for:**
- **New construction**: framing, sheathing, trim. - **Additions and remodels**: replacing structural elements. - **Decks and outdoor structures**: pressure-treated lumber, cedar, redwood. - **Fences**: posts, rails, pickets. - **Garages and sheds**: full structural systems. - **Furniture projects**: hardwood and softwood components. - **Renovations**: replacement joists, headers, walls.
**Framing best practices:**
- **Use kiln-dried lumber for indoor framing**: less warping after install. - **Pressure-treated for ground contact**: posts, sill plates, joists in damp areas. - **Engineered lumber for long spans**: I-joists or LVL beams instead of larger dimensional. - **Standard lengths**: 8, 10, 12, 16 ft (16 ft is most economical for most uses). - **Buy slightly long**: cut to exact length on site rather than trying to use exact-length boards.
**Choosing the right grade:**
- **Hidden framing**: #2 or even Utility grade. - **Visible framing (exposed beams, posts)**: Select or #1. - **Decking**: cedar #1 or pressure-treated above-ground. - **Posts (ground contact)**: pressure-treated UC4A grade. - **Foundation sill plates**: pressure-treated. - **Premium exterior**: cedar or redwood clear grade.
**Lumber dimensions you actually get:**
Always order in nominal sizes (2×4, 2×6, etc.) but plan with actual sizes (1.5×3.5, 1.5×5.5). For finished work where 1/8" matters (cabinetry, trim), measure each piece before cutting.
**Buying strategy:**
- **Lumber yards**: best selection, knowledgeable staff, accept returns. - **Big-box stores**: convenient, sometimes lower prices on common items. - **Sawmills**: cheapest but often rough-sawn, limited species. - **Online**: specialty items, hardwoods, custom sizes.
**Pricing tip:**
Lumber prices fluctuate significantly. Get quotes from multiple sources for large projects. Spring/summer (peak season): highest prices. Fall/winter: lower prices, especially February-March before construction season.
**Permit requirements:**
- New construction: building permits required. - Additions: permits and engineering drawings. - Decks: permits required in most jurisdictions for size > 200 sq ft or > 30" off ground. - Fences: permits required in many jurisdictions, especially over 6 ft. - Sheds: usually permit-free under specific size limits (100-200 sq ft).
**Storage and handling:**
- Stack flat with stickers between layers for airflow. - Cover for weather but allow ventilation. - Keep away from direct ground contact. - Use as soon as possible — extended storage degrades wood.
**Wood movement and humidity:**
Lumber expands and contracts with moisture. Allow indoor lumber to acclimate 1-2 weeks. Outdoor lumber expands ~3-5% across the grain in wet vs dry conditions. Design joints to accommodate movement (gaps in decking, etc.).
**Common warnings:**
- Pressure-treated lumber has chemical residue — wear gloves, dispose properly. - Don't burn pressure-treated wood (toxic fumes). - Some species cause skin reactions or splinter easily. - Old (pre-1980) painted lumber may contain lead.
Common mistakes to avoid
- Ordering wrong dimensional size. 2×4 is 1.5×3.5 actual; verify before cutting.
- Using untreated wood for ground contact. Untreated rots within years; use PT for ground.
- Mixing wet and dry lumber. Different moisture content causes uneven shrinkage.
- Buying too little. Last-minute orders may have different grain/color than original.
- Using construction-grade lumber for visible work. Defects show; pay for select grade for visible.
- Skipping permits. Required for most structural work; consequences are significant.
- Ignoring code spans. Over-spanning joists/beams leads to structural failure.