Hardwood Board & Lumber Sizes

If you are planning on building furniture or cabinets or you are using hardwood boards (Figure 1) in another wood working project, it is important that you understand the dimensions of finished hardwood boards and their other characteristics.

Figure 1 - Hardwood boards

Hardwood boards (lumber) that are sold for use in furniture, cabinets or other finished work are specified in a different manner than most softwood boards.

Hardwood boards are generally sold based on the quarter system. A board that is 4/4 is a board that prior to milling was 1 inch thick.

Note: In some cases decking boards or lumber are sold using the quarter system of measurement.

When the lumber yard tells you that they have 4 quarter hardwood boards available, it means that the hardwood boards that they have were 1 inch thick before they were milled.

Note: The correct method to write the thickness of a piece of hardwood lumber using the quarter system is X/4, where X is the number of quarters.

As well, hardwood boards are designated by their surface finish, which also changes the milled size of the lumber:

• A hardwood board that is finished on one side is called S1S which stands for surface finished on one side.
• A hardwood board that is finished on two sides is called S2S which stands for surface finished on two sides.

Table 1 provides the finished size of a hardwood board, depending on how many surfaces have been finished and its quarter system designation.

* 5/8 inch thick boards are not dimensioned using the quarter system.

Having the second surfaced finished reduces the hardwood boards dimensions by 1/16th of an inch.

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