While most home centers use nominal dimensional sizes (such as 2x4) to describe their lumber, most hardwood lumber retailers rely on the quarter system to classify their products. While unfamiliar at first, the quarter system is easy to navigate once you know what the different sizes are called.
The quarter equates to ¼”. So, if you see a piece of wood described as 4/4 or said as “four-quarter”, then it is four ¼” or, more simply, 1”. Being able to describe lumber in this fashion helps when calculating board footage, which can help you estimate the cost of the lumber you need.
Something to keep in mind, however, is that the lumber at the House of Hardwood is S2S, meaning that the two faces are surfaced, allowing you to see the grain and have a better reference surface. Due to this, our lumber is 3/16” less than what the quarter system would immediately suggest (ie. 4/4 is now 13/16”). Here is a cheat sheet of common House of Hardwood lumber sizes: