Board Foot Calculator

Calculate lumber volume in board feet for any cut list.

Lumber size Thickness (in) Width (in) Length (ft) Quantity Price per board foot $ (optional)

What is board foot calculator?

A board foot is the standard unit of lumber volume: nominal thickness (in) × width (in) × length (ft) / 12. Lumber yards quote rough stock in board feet, hardwood dealers price by the bd ft, and framing takeoffs roll up into board-foot totals for ordering.

This calculator handles every common dimensional size — 1×4 trim, 2×4 studs, 2×8 joists, 6×6 posts — plus quarter-system hardwoods like 5/4 decking and 8/4 turning blanks. Add an optional price per bd ft and it returns the total cost so you can compare yard quotes side by side.

The math uses nominal dimensions: a 2×4 counts as 2 × 4, not its actual planed 1.5 × 3.5. That’s the same convention your lumber yard uses on every quote, so the totals here match the line items on a yard’s invoice.

When to use a board foot calculator

Framing-lumber takeoff — Total the board feet for a stick-framed wall, deck, or shed and price it against your yard's bd-ft rate.
Cabinet and furniture stock — Estimate hardwood lumber for a face frame or table top so you can buy with minimal waste.
Comparing dimensional choices — See how switching from 2×6 to 2×8 joists changes both the structural span and the board-foot total of the order.

How to use the Board Foot Calculator

Choose a lumber size — Select a preset (1×4 through 6×6) or pick Custom to enter your own thickness and width.
Enter length and quantity — Length is in feet. Quantity is the number of identical pieces.
(Optional) add a price — Type your yard's quote in dollars per board foot to see the total cost.

Worked examples

Wall plate run — 30 ft of 2×4 plate (3 pieces × 10 ft)

Input:  Thickness=2, Width=4, Length=10, Qty=3
Output: 6.67 bd ft per piece, 20 bd ft total

Deck joists — 14 × 2×8 × 12 ft

Input:  Thickness=2, Width=8, Length=12, Qty=14
Output: 16 bd ft per piece, 224 bd ft total

Walnut tabletop blanks — 6 × 5/4 × 8 × 6 ft at $9.50/bd ft

Input:  Thickness=1.25, Width=8, Length=6, Qty=6, $9.50/bf
Output: 5 bd ft per piece, 30 bd ft total, $285.00 total

Frequently asked questions

How is board foot calculated?

Board feet = (thickness in inches × width in inches × length in feet) ÷ 12. So a 2×6 × 8 ft board is (2 × 6 × 8) ÷ 12 = 8 bd ft.

What's the difference between board feet and linear feet?

Linear feet is just length — 10 ft is 10 linear ft no matter the size of the board. Board feet accounts for the cross-section too, so a 10-ft 2×4 (6.67 bd ft) is half the volume of a 10-ft 2×8 (13.33 bd ft).

Should I use nominal or actual dimensions?

Nominal. A 2×4 is actually 1.5 × 3.5 after planing, but lumber pricing has always been based on the rough nominal callout. Enter 2 and 4.

How do I enter quarter-system sizes like 5/4 or 8/4?

As decimals. 5/4 = 1.25, 6/4 = 1.5, 8/4 = 2. These are common in hardwood lumber where rough thickness is sold by the quarter inch.

How much waste should I add?

10–15% for typical framing is a safe overage to cover cuts, defects, and small mistakes. Add it by bumping your quantity, not by inflating the dimensions.

Why does the price total seem high?

Per-board-foot lumber pricing can compound quickly on larger projects. Cross-check the yard's quote line by line, and confirm whether their rate is for surfaced (S4S) or rough lumber — the difference can be 20–30%.

Can I print or save this?

Use the Copy summary button to grab the totals into a clipboard, then paste them into a doc, email, or spreadsheet.

Board Foot Calculator

Wall plate run — 30 ft of 2×4 plate (3 pieces × 10 ft)

Deck joists — 14 × 2×8 × 12 ft

Walnut tabletop blanks — 6 × 5/4 × 8 × 6 ft at $9.50/bd ft

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