5/4x12 actual size

Dry (19% moisture or less)

1 × 11-1/4 in

25.4 × 285.8 mm

From the standard, NIST PS 20-25

End view to scale: dashed is the nominal 5/4x12, filled is the dry dressed size.

Nominal, dry and green

Size	Thickness	Width
Nominal (the name)	1-1/4 in	12 in
Dry, minimum	1 in (25.4 mm)	11-1/4 in (285.8 mm)
Green, minimum	1-1/32 in (26.2 mm)	11-1/2 in (292.1 mm)

A 5/4x12 is boards (under 2 in nominal thickness) under the American Softwood Lumber Standard, NIST PS 20-25. The standard names lumber by its nominal size and sets the smallest it may be once it has been dressed (planed smooth). Lumber dried to 19% moisture content or less is held to the dry size; lumber surfaced green, above 19%, is left a little bigger because it shrinks as it dries.

Board feet in a 5/4x12

Thickness × width ÷ 12 gives the board feet in each foot of length. By the nominal size that is 1.25 bd ft per foot; by the dry dressed size it is 0.938. Ask your yard which one it prices on.

Length	Nominal bd ft	Actual (dry) bd ft
8 ft	10	7.5
10 ft	12.5	9.38
12 ft	15	11.25
16 ft	20	15

For a whole order, use the board foot calculator. Every size side by side is on the lumber sizes chart.

What a 5/4x12 weighs per foot

One foot of a dry 5/4x12, 1 × 11-1/4 in, at 12% moisture content: its volume × the Wood Handbook’s density, 62.43 lb/ft³ × the species’ specific gravity at 12% × 1.12. Multiply by the length for a whole board. Wetter wood weighs more; the wood weight calculator takes any moisture content.

Species	Specific gravity (12%)	Weight per foot
Douglas-fir (coast)	0.48	2.62 lb
Southern pine (loblolly)	0.51	2.79 lb
Western hemlock	0.45	2.46 lb
Eastern white pine	0.35	1.91 lb
White spruce	0.36	1.97 lb

One source: USDA Forest Products Laboratory, the authority for species properties it measured

Work it out for your project

Estimate the lumber for a whole project
List the parts, get the boards and board feet to buy, with waste.

Sources

How we source these numbers