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 Lumber & Framing Calculators
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.
Accuracy & Review
Reviewed by: Liam Santos
Liam reviews our decking, lumber, and board foot calculators to confirm accurate framing takeoffs, dimensional lumber calculations, and waste assumptions. He focuses on ensuring estimates reflect practical framing layouts and real-world material usage.
Last updated:
See: Methodology · Data Sources · Review Board
Important Estimate Disclaimer
These estimates are for general planning purposes only and should not be used as structural design guidance. Actual lumber quantities depend on span limits, load requirements, material grade, and building code compliance.
See our Methodology and Data Sources for reference information.
Structural framing components should be verified against current code requirements before construction.