Lumber Calculator
Timber quantity and cost — board feet, cubic meters, linear length and price — from the section size and the number of pieces.
How much timber to order and what it costs.
How the lumber calculator works
Timber is sold three different ways and the units rarely match the way it is measured. Board feet (nominal thickness in inches × width in inches × length in feet ÷ 12) is the North American convention; metric markets sell by linear meter for a given section, or by cubic meter for bulk.
This converts between all three so a quote in one unit can be compared against a quote in another.
Formula: board feet = t(in) × w(in) × L(ft) / 12
Worked examples
| Inputs | Total linear length | Note |
|---|---|---|
| Twenty 45 × 90 × 2.4 m | 52.8 | 52.8 m, 0.214 m³ |
| A larger section | 33.6 | heavy structural timber |
| No waste allowance | 48 | exactly 48 m |
FAQFrequently asked questions
What is a board foot?
A volume: 1 inch thick × 12 inches wide × 1 foot long, or 2,360 cm³. It is the North American unit for rough-sawn timber.
How many board feet in a cubic meter?
About 424.
Why do nominal and actual sizes differ?
Because nominal refers to the rough-sawn size before dressing. A US "2 × 4" finishes at 1.5 × 3.5 inches; Australian 45 × 90 is the finished size.
How much waste should I allow?
10% for straightforward work, 15% or more where there are many short cuts or you are selecting around defects.
Which unit will my supplier quote?
Linear meter for a given section in metric markets, board feet in North America, cubic meter for bulk anywhere. This converts between all three.
Where these figures come from
- The Engineering ToolBox — material densities, coverage and unit data — bulk densities, concrete at 2,400 kg/m³, board and sheet sizes
- Gypsum Association — gypsum board sizes — 4 × 8 and 4 × 12 ft sheets
- ADA Standards for Accessible Design — ramps (§405) — maximum running slope 1:12
- International Code Council — the International Residential Code
Last checked: September 2026. Coverage rates and material sizes are typical manufacturer figures — check the product you buy.