Lumber Calculator – Fast, Accurate Material Estimates
Use this free lumber calculator to size materials for common projects. Whether you’re framing a room, running skirting or fascia boards, or laying down sheets of plywood/OSB, this tool gives you quick piece counts, board feet (BF) or cubic meters (m³), estimated offcuts, and optional cost. It supports both metric and imperial units and uses real-world defaults with editable waste.
How the Lumber Calculator Works
- Nominal vs actual sizes: You pick the nominal size (e.g., 2×4 or 90×45). The calculator uses the actual finished dimensions to compute volume precisely.
- Board feet / m³: Imperial projects use board feet (BF), calculated from thickness × width × length ÷ 144. Metric projects use cubic meters (m³).
- Waste allowance: Add 5–15% to cover trim cuts, knots/defects, and handling losses. You control the percentage.
- Stock lengths: Choose the lengths you can actually buy. A simple greedy optimizer packs cuts to reduce offcuts.
- Pricing: Enter a price per piece and/or a price per BF/m³ to get a quick cost breakdown.
Framing Lumber: Studs & Plates
For stud walls, counts are driven by wall length, stud spacing (e.g., 400 mm / 16 in), and wall height. Corner studs and simple opening rules (doors/windows) are included, plus single or double top plates. You’ll see the number of studs, plate pieces by stock length, and overall volume for ordering.
Boards & Trim: From Linear Run to Pieces
Enter a total linear run and select the sizes and stock lengths you plan to purchase. The tool converts to pieces, estimates offcuts, and reports board feet/m³. This is ideal for skirting, fascia, picture rails, handrails, and general trim.
Sheet Goods: Plywood & OSB
Provide the area length and width and pick a standard sheet size (e.g., 1220×2440 mm or 4×8 ft). The calculator returns sheet counts and total coverage with your waste allowance, perfect for floors, walls, and roofs.
Related Project Calculators
- Plywood Calculator – plan sheet counts and coverage precisely.
- Deck Calculator – estimate joists, decking boards, and hardware.
- Drywall Calculator – get sheet, screw, and compound estimates.
FAQs
What’s the difference between nominal and actual lumber size?
Nominal sizes (like 2×4) are the rough-cut names. Actual sizes are smaller after drying/planing (e.g., 1½″×3½″). The calculator uses actual dimensions for accurate volume.
How much waste should I allow?
10% is a sensible default for most jobs. Complex cuts, lots of angles, or premium clear stock may warrant more.
Can I price by board foot or by m³?
Yes. Enter a price per BF (imperial) or per m³ (metric). If you also enter a price per piece, you’ll see both estimates for comparison.
Estimates only. Always check local codes, supplier availability, and on-site conditions before ordering.