Lumber weight and price calculator

Before you optimise a cutting list, it pays to know how much lumber you actually need, what it will weigh, and what it will cost. This guide walks through the formulas so you can size up a project in minutes and feed accurate numbers into the OptimalLayout cut optimizer.

1. Board feet — the universal lumber unit

One board foot is a piece 1 inch thick, 12 inches wide and 12 inches long (144 in³ of nominal volume). The formula is:

Board feet = (Thickness in × Width in × Length ft) ÷ 12

Example: a 2×4 that is 8 ft long → (2 × 4 × 8) ÷ 12 = 5.33 board feet. Multiply by your price per board foot to get the cost.

2. Volume in metric (m³)

Outside North America, lumber is usually sold by the cubic metre. Convert all three dimensions to metres and multiply:

Volume (m³) = Thickness × Width × Length (all in metres)

Example: 38 × 89 × 2400 mm → 0.038 × 0.089 × 2.4 = 0.00812 m³. A m³ of construction-grade softwood typically costs €350–€600 depending on species and region.

3. Weight — density × volume

Weight matters for shipping, for floor loading, and for working out whether you can lift a sheet on your own. Multiply volume by the species density:

• Pine / SPF: ~470 kg/m³ (29 lb/ft³)
• Douglas fir: ~530 kg/m³ (33 lb/ft³)
• Oak (red/white): ~720 kg/m³ (45 lb/ft³)
• Maple, hard: ~705 kg/m³ (44 lb/ft³)
• Walnut: ~610 kg/m³ (38 lb/ft³)
• Plywood, softwood: ~550 kg/m³ (34 lb/ft³)
• MDF: ~750 kg/m³ (47 lb/ft³)
• Particle board: ~680 kg/m³ (42 lb/ft³)

A full 18 mm MDF sheet (2440 × 1220 mm) therefore weighs about 0.018 × 2.44 × 1.22 × 750 ≈ 40 kg — a two-person lift.

4. Price — three ways to quote it

• Per board foot (US hardwood dealers): Total = board feet × $/BF
• Per linear foot or metre (dimensional softwood): Total = length × price/length
• Per sheet (plywood, MDF, OSB): Total = sheets needed × price/sheet

Always add 10–15 % for defects, off-cuts and the saw kerf — even with a good cutting list, real sheets have grain, knots and edge damage you will trim away.

5. Feed the numbers into OptimalLayout

Once you know the part sizes, open the cut optimizer and enter your base sheet or board dimensions plus each part. The optimizer returns the minimum number of sheets, total cut length and a labelled diagram — so the lumber you actually buy matches your estimate, with as little waste as possible.

Quick reference

• Board feet = (T_in × W_in × L_ft) ÷ 12
• Volume m³ = T_m × W_m × L_m
• Weight kg = Volume m³ × density kg/m³
• Add 10–15 % waste before ordering
• Use OptimalLayout to confirm the real sheet count