Hardwood Lumber Sizes and Buying Guides

Published: September 12, 2022

With nominal dimensions being widely used when selling softwoods, some large retailers have extended the practice to hardwood boards as well. Your local home center probably stocks a few species of hardwoods, like oak, maple and cherry. These boards generally are planed to 3/4-inch thick, jointed flat on the edges and cut to standard widths and lengths. Within the lumber industry, hardwood lumber like this is categorized as "S4S", which stands for Surfaced Four Sides. All of this surface preparation at the mill translates to higher prices for you, but it may make the most sense to buy S4S lumber if you don't own a thickness planer or jointer to prepare board surfaces yourself.

To find specialty or thicker hardwoods, you'll need to expand your wood shopping outside the big box stores. A good lumber supplier will offer a wide selection of hardwoods in random widths and in an assortment of thicknesses and grades. In addition to S4S, you'll see S2S lumber which is planed smooth on two faces but the edges are rough, and rough sawn boards which are boards that are simply cut, dried and shipped to the lumberyard.

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Because of the diversity of uses, hardwoods are typically sold in a much larger variety of thicknesses than standard 1x and 2x softwoods are sold by. This has led to a quartering system for determining lumber thickness, which allows you to buy hardwoods in 1/4-inch thickness increments from 3/4-inch on up.

Most yards offer popular hardwood species in three, four, five, six, eight, ten and even twelve quarter thicknesses which are read as 3/4, 4/4, 5/4, 6/4, 8/4, 10/4 and 12/4 on the label at the rack. These correspond to the rough pre-planed thicknesses of 3/4-inch, 1-inch, 1 1/4-inch, 1 1/2-inch, 2 inch, 2 1/2-inch and 3 inch.

Hardwood Surfacing Options

If the extent of your hardwood needs amounts to only an occasional project, buy S4S boards at the yard. They'll come planed on both faces and jointed flat on both edges, ready for breaking down into parts for your project.

If you have access to a jointer, consider buying S2S lumber, which still has rough edges but the faces are planed smooth. The most economical hardwood comes rough sawn to the lumberyard and will require you to do all of the surface preparation yourself. If you don't own a planer some lumber yards will plane your lumber for a nominal fee.

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Hardwood Lumber Grades

Hardwood lumber is graded using a different classification system than softwoods. Grades are based on the percentage of clear face cuts that can be made around a board's defects knots, splits, pitch pockets, and so forth. From highest grade to lowest (most allowable defects). The grades are:

Grade	Percentage of Clear Cuts
FAS (Firsts & Seconds)	83 1/3%
Select	83 1/3%
No. 1 Common	66 1/3%
No. 2A & 2B Common	50%
No. 3A Common	33 1/3%
No. 3B Common	25%

Choose the lumber grade that best suits the needs of your project and your budget. It could be that a Common grade will provide all the knot-free lumber you need at a significant savings over FAS.