4x4 lumber: actual size and cut list

Actual size of a 4x4

Nominal	4 × 4 in
Actual (dressed)	3 1/2 × 3 1/2 in
Metric	89 × 89 mm
Common lengths	8, 10, 12, 14 and 16 ft (2.4–4.8 m)

Softwood dimensional lumber is named by its rough-sawn size. Drying and planing on all four sides takes it down to the dressed size, which is what you measure and what goes into your cut list. Lengths are usually true, and many yards cut boards slightly long, but check the ends for splits and snipe and set an end trim if needed.

Board feet per 4x4

Board	Board feet	Actual volume
4x4 × 6 ft	8.00	14.5 L
4x4 × 8 ft	10.67	19.3 L
4x4 × 10 ft	13.33	24.1 L
4x4 × 12 ft	16.00	28.9 L
4x4 × 14 ft	18.67	33.7 L
4x4 × 16 ft	21.33	38.5 L

Board feet use the nominal size, so a 4x4 × 8 ft is 10.67 BF even though less wood is actually there. Calculate mixed orders with the board foot calculator.

How many pieces from one board?

Full pieces per board with a 1/8-inch kerf. A piece that ends exactly at the end of the board needs no extra cut.

Piece length	8 ft board	10 ft board	12 ft board
12″	7	9	11
16″	5	7	8
18″	5	6	7
24″	3	4	5
30″	3	3	4
32″	2	3	4
36″	2	3	3
48″	1	2	2

Common uses

• Deck and fence posts
• Table and bench legs
• Pergola posts
• Mailbox posts

FAQ

What are the actual dimensions of a 4x4?

A 4x4 is actually 3 1/2 × 3 1/2 inches (89 × 89 mm) after drying and planing. The nominal size is the rough-sawn size before surfacing.

How many board feet are in a 4x4 × 8 ft?

10.67 board feet, using the nominal 4 × 4 inch size as lumber yards do: 4 × 4 × 8 ÷ 12.

How many 24-inch pieces can I cut from an 8 ft 4x4?

3 with a 1/8-inch kerf — the fourth piece comes out 3/8 inch short, so you get three full 24-inch pieces and a 23 5/8-inch offcut.