Actual Dimensions (wood)

This is the term used to reference the exact dimensions of standard lumber and their measurements in inches.

“Actual dimensions” goes hand-in-hand with “nominal dimensions”, which is used to describe a piece of wood as it is first cut at the mill (rough cut) before getting planed and sanded down to its actual dimension. 

This “final” measurement is what is shipped and sold to suppliers, lumber yards and big box stores.

Lengths of wood pieces are always referred to separately from wood dimensions, such as an 8′ 2 x 4 (two-by-four).

So, what are actual dimensions of standard lumber and wood pieces?

Measurements below are listed by nominal dimensions first, as these measurements are what are commonly known and used when referring to these wood sizes.

Nominal to Actual Wood Dimensions

  • “1 x 2″ = 3/4″ thick x 1 1/2” wide (19 mm × 38 mm)
  • “1 x 3″ = 3/4″ thick x 2 1/2” wide (19 mm × 64 mm)
  • “2 x 4″ = 1 1/2″ thick x 3 1/2” wide (38 mm × 89 mm)
  • “2 x 6″ = 1 1/2″ thick x 5 1/2” wide (38 mm × 140 mm)
  • “4 x 4″ = 3 1/2″ thick x 3 1/2” wide (89 mm × 89 mm)
  • “6 x 6″ = 5 1/2″ thick x 5 1/2” wide (140 mm × 140 mm)

Less common wood sizes’ actual dimensions

  • “1 x 4″ = 3/4″ thick x 3 1/2” wide (19 mm × 89 mm)
  • “1 x 6″ = 3/4″ thick x 5 1/2” wide (19 mm × 140 mm)
  • “1 x 8″ = 3/4″ thick x 7 3/4” wide (19 mm × 184 mm)

Architects, contractors, and carpenters speak to wood dimensions as they are called, but actually do their work under the real measurements so that every fractional inch is accounted for correctly when planning and building structures, or any product made from wood.

So, if you’re planning a building project with “2 x 4”, make sure you measure everything out using the 1 1/2″ x 3/4″ measurement to get things right.