A “2 by 6” or 2×6 is a common dimensional lumber size rounded to two inches by six inches before final milling, and is sold in a variety of standardized lengths from 8′ up to 20′. After milling, the standard two by six is actually sold at approximately 1.5 inches by 5.5 inches. 2by6s are the stronger, version of a standard 2×4 primarily used in building framing and construction.

Dimensional soft wood lumber (called timber in the UK and many of its former colonies outside of the United States) is usually made from Spruce-Pine-Fir (SPF), and other conifer woods. Other standardly available sizes range from 1×2 to 8×8 and are regulated for quality control by governments and organizations based on various criteria across much of the world.

In contrast to dimensional soft wood lumber, hardwoods are sold to end consumers by the board-foot and used for many visible, functional, and finished wood products. Hardwoods are also used in construction in places where softwoods don’t grow as well.

A board foot is a unit of measurement for the volume of lumber in the Unites States and Canada. It equals the volume of a board that is one foot (30.5 cm) in length, one foot (30.5 cm) in width, and one inch (2.54 cm) in thickness, or 2.36 liters.