There have been a number of different standards for the inch in the past, with the current definition being based on the international yard. History/origin: The term "inch" was derived from the Latin unit "uncia" which equated to "one-twelfth" of a Roman foot. There are 12 inches in a foot and 36 inches in a yard. An inch was defined to be equivalent to exactly 25.4 millimeters in 1959. Inchĭefinition: An inch (symbol: in) is a unit of length in the imperial and US customary systems of measurement. Height is commonly measured in centimeters outside of countries like the United States. Learning some of the more commonly used metric prefixes, such as kilo-, mega-, giga-, tera-, centi-, milli-, micro-, and nano-, can be helpful for quickly navigating metric units.Ĭurrent use: The centimeter, like the meter, is used in all sorts of applications worldwide (in countries that have undergone metrication) in instances where a smaller denomination of the meter is required. Metric prefixes range from factors of 10 -18 to 10 18 based on a decimal system, with the base (in this case the meter) having no prefix and having a factor of 1. History/origin: A centimeter is based on the SI unit meter, and as the prefix "centi" indicates, is equal to one hundredth of a meter. This means a 2×8 actual size is 1 1/2 inches in its thickness by 7 1/4 inches.Definition: A centimeter (symbol: cm) is a unit of length in the International System of Units (SI), the current form of the metric system. The larger 2x boards (2×10, 2×8, etc.) lost 3/4 inches of their width. This means a 2×4 board is actually 3-1/2 inches by 1-1/2 inches. 2x Board SizesĢ×6 and 2×8 boards lost 1/2 inches in thickness and 1/2 inches in its width just prior to leaving the mill. This means a 1×10 is actual 3/4 inches in its thickness by 9 1/4 inches. The larger 1x boards (1×10, 1×8, etc.) lose 3/4 inches in their width. Modern sawmills mostly account for this, and dimensional lumber is generally quite consistent.ġ×6 and 1×4 boards lose 1/4 inch in thickness and 1/2 inch in their width prior to leaving the mill which means a 1×4 board is actually 3 1/2 inches by 3/4 inches. These days, boards are deliberately cut into large in order to allow the shrinkage while the milling procedure and kiln drying.Īs the amount of a board that shrinks may vary by moisture content, wood species, and the individual tree, so the final size may also vary slightly. In history, the softwood logs were cut into 2 x 8, but they naturally shrink as boards dry, and after milling and planing, they end up on 1.5×7.25. Why dimensional lumber is smaller as compared to nominal dimensions?
If the nominal size is equal to 8” or larger than this, then its actual size will be 3/4” inches smaller.If the nominal size is less than 1,” then the actual size of the board will be 1/4” inches less than the nominal size.You may use a simple thumb rule that is to ascertain the actual size of dimensional lumber.
The board which is advertised and being sold by using nominal dimensions is a bit larger in size as compared to the actual size. These are the dimensions of the board prior to it being milled and dried.īut in reality, the actual sizes of a board are a bit smaller than the actual ones.įor instance, a 2×8 board is referring to having 1 1/2 x 7 1/4 inches (38 x 184 mm) dimensions in actuality. Most of the softwood lumber that has been sold at the lumber yard store is dimensional lumber.ĭimensional lumber is basically lumber that has been milled and dried to standard dimensions and is mostly used for construction and framing.ĭimensional lumber is being sold by using those nominal dimensions of the board that are not actual. Although, there is a small difference between the actual size and the nominal size (to whom the framing lumber is being referred). You might have seen the frame softwood boards or framing lumber that is being sold at any local hardware store or lumber yard that advertised those dimensions that do not match the actual size of the frame board.ĭimensional lumber is being cut to a specific width, length, and depth.
A 2×8 board is 1 1/2 x 7 1/4 inches (38 x 184 mm) dimensions in actuality.