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Board Feet Calculator
Computes board feet (the US lumber volume unit: 1 board foot = 144 cubic inches = a 1 in × 12 in × 12 in board) from nominal thickness and width in inches and length in feet, for a given quantity, with the total cost at a price per board foot.
When to use
You are pricing or ordering hardwood or rough lumber sold by the board foot, or converting lumber dimensions into board feet, cubic feet or cubic metres.
Do not use when: Lumber is sold by the linear foot or piece (dimensional softwood such as 2 × 4 studs), or you need deck board counts (use decking).
Formula
board_feet = thickness_in × width_in × length_ft / 12 (equivalently T × W × L_in / 144); total = board_feet × quantity; cost = total × price_per_board_foot; ft³ = board_feet / 12; m³ = ft³ × 0.028316847.
Board footage uses nominal (rough-sawn) dimensions: a surfaced 4/4 board that measures 13/16 in is still counted as 1 in thick. Some yards round each board's width to the nearest inch before calculating.
Inputs
| Parameter | Type | Unit | Required | Description |
|---|---|---|---|---|
thickness_in | number | in | yes | Nominal thickness in inches (hardwood is often quoted in quarters: 4/4 = 1 in, 8/4 = 2 in). Range: > 0, ≤ 48 |
width_in | number | in | yes | Nominal width in inches. Range: > 0, ≤ 120 |
length_ft | number | ft | yes | Length in feet. Range: > 0, ≤ 200 |
quantity | integer | default 1 | Number of identical pieces. Range: ≥ 1, ≤ 100000 | |
price_per_board_foot | number | no | Optional unit price; enables the total cost. Range: ≥ 0 |
Outputs
| Output | Type | Unit | Description |
|---|---|---|---|
board_feet_each | number | bd ft | thickness_in × width_in × length_ft / 12. |
board_feet_total | number | bd ft | board_feet_each × quantity. |
total_cost | number | board_feet_total × price_per_board_foot; only when a price is given. | |
volume_cubic_feet | number | ft³ | board_feet_total / 12. |
volume_m3 | number | m³ | Total volume in cubic metres (1 bd ft = 0.002359737 m³). |
Example
Ten 1 × 6 boards, 8 ft long, at $5 per board foot: {"thickness_in":1,"width_in":6,"length_ft":8,"quantity":10,"price_per_board_foot":5} → {"board_feet_each":4,"board_feet_total":40,"total_cost":200,"volume_cubic_feet":3.3333,"volume_m3":0.09439}
One 2 × 4, 8 ft long: {"thickness_in":2,"width_in":4,"length_ft":8} → {"board_feet_each":5.333,"board_feet_total":5.333,"volume_cubic_feet":0.4444}
GET https://tttkmbb.com/api/v1/calculate/board-feet?thickness_in=1&width_in=6&length_ft=8&quantity=10&price_per_board_foot=5
Machine access
- API:
GET https://tttkmbb.com/api/v1/calculate/board-feet(query parameters) orPOSTwith a JSON body{"inputs": {...}} - Schema: https://tttkmbb.com/api/v1/calculators/board-feet · Markdown: https://tttkmbb.com/construction/board-feet.md · JSON definition: https://tttkmbb.com/construction/board-feet.json
- MCP: server
https://tttkmbb.com/mcp, toolrun_calculator with calculator_id="board-feet" - OpenAPI operationId:
calculate_board_feet - Freshness:
static. Authentication: none. Rate limit: fair use (see rate limits).
Sources
FAQ
Do I use nominal or actual dimensions?
Nominal. A 2 × 4 counts as 2 in × 4 in even though it measures 1.5 in × 3.5 in; hardwood thicknesses are quoted in quarters (5/4 = 1.25 in) of nominal thickness.
How do I convert a length in inches?
Divide by 12 to get feet, or use T × W × L(in) / 144, which gives the same board feet.
Related calculators
- Decking Calculator — Board counts for a deck.
- Volume Converter — Convert cubic feet and cubic metres.
- Rectangular Prism Calculator — General box volume.