Woodworking plane numbers generally refer to the length and width of the blade in inches. These numbers help categorize and differentiate between various sizes of planes available in the market, allowing craftsmen to choose the most suitable tool for their specific needs. For instance, a No. 4 bench plane typically has a blade that measures around 2 inches wide by 9-10 inches long, whereas a No. 5 would have a slightly wider blade at around 2.25 inches. The larger the number, the wider and longer the blade becomes. Woodworkers often select plane numbers based on the scale of their projects; smaller planes like No. 1 or No. 2 are handy when working on intricate details or delicate pieces, while larger planes offer more efficiency and coverage for bigger tasks.