4/4, 8/4, FAS: Buying Rough Lumber Without Getting Skinned

The first trip to a real hardwood dealer is intimidating in a specific way. The boards are stacked rough and gray, stamped in crayon with things like 4/4 and 8/4 and FAS, and priced by the board foot instead of the piece. It feels like a members-only club with a language you never learned. It is not. Decode four ideas — quarters, board feet, grades, and what "rough" actually costs you — and you will buy like you belong.

Quarters: thickness in quarter-inches

The stamped fractions are rough thickness measured in quarters of an inch. 4/4 is "four-quarter," one inch rough. 5/4 is an inch and a quarter, 6/4 is an inch and a half, 8/4 is two inches. It reads oddly at first because nobody reduces the fractions — 4/4 is never written as 1 — but that is the convention, a holdover from mills that cut in quarter-inch steps.

The catch that skins beginners: rough thickness is not usable thickness. A 4/4 board is about an inch as it sits, but after you flatten one face, thickness the other, and clean it up, you net roughly three-quarters of an inch of flat, usable wood — a bit more if you are careful and the board is straight. So you buy the quarter above your finished dimension. Need three-quarter-inch parts? 4/4 is right. Need an inch-and-a-half leg? Buy 8/4 and expect to land near an inch and three-eighths. Never buy 4/4 expecting a full, flat inch.

Board feet: the volume you actually pay for

Hardwood is sold by the board foot, a unit of volume, not by the running foot or the piece. One board foot is 144 cubic inches — think one inch thick, twelve inches wide, twelve inches long, or any equivalent chunk. The formula is worth memorizing:

Board feet = (thickness in inches x width in inches x length in inches) / 144.

Use the rough thickness in the calculation, because that is what the mill cut and what you are charged for. An 8/4 board six inches wide and eight feet long works out to (2 x 6 x 96) / 144 = 8 board feet. At nine dollars a board foot, that plank is seventy-two dollars. Run the numbers at the rack, on your phone if you have to, not at the register where it is too late to put it back.

Grades: FAS down to Common

Hardwood grades come from the National Hardwood Lumber Association, and they describe how much clear, defect-free wood you can cut out of a board — graded off its worse face. The names sound fancier than the idea:

• FAS (Firsts and Seconds) is the top grade: long, wide, clear cuttings, the best choice when you need long clear parts like a tabletop or a rail. It is also the priciest.
• Select (SEL) is FAS-quality on the good face with a more relaxed back face — a smart buy when only one face of the part will show.
• #1 Common (1C), often called cabinet grade, yields shorter clear cuttings between more knots and defects. If your project breaks down into small parts anyway, it yields nearly as much usable wood as FAS for a lot less money.
• #2 Common is shop and paint grade, fine for jigs, drawer bottoms, and anything getting painted.

The insider move is to match the grade to your cut list, not to the prestige of the letters. For a project cut into small pieces, #1 Common often delivers the same usable wood as FAS at a real discount, because you were going to cut around the defects regardless. Reserve FAS for when you genuinely need long, wide, clear boards.

Reading the crayon

The stamps on the ends tell a short story: the quarter thickness (4/4), sometimes a grade (FAS, SEL, 1C), often KD for kiln-dried, and sometimes the footage of that board. They are lumber-crayon strokes, a little rotated, a little imperfect — that is what a working stack looks like, not a defect. KD matters: kiln-dried stock has been brought down to a workable moisture content, and building with wet wood is how you get joints that fail when the piece dries out in a heated house.

Rough means you do the milling

Rough lumber is not flat, not square, and not final thickness. Between you and finished parts is the milling: flatten one face, square one edge to it, then bring the board to final thickness and rip to width. That process sheds an eighth to a quarter inch of thickness and some width, and every board hides cup, bow, twist, or end checks you will cut around. Plan on roughly fifteen to twenty percent waste for a straightforward project, more for figured or twisted stock. Sight down every board before you load it, and reject the ones that look like propellers.

Breaking down rough stock

You can dimension entirely by hand — a scrub plane to hog off the high spots, a jointer plane and winding sticks to get a face flat and true — and it is a genuinely satisfying skill. Most hybrid shops, though, rough-crosscut boards to manageable lengths and then rip near final width by machine, and a compact contractor saw handles that job in a one-car garage. The DEWALT DWE7485 is the most-gifted "first real saw" precisely because it does this without needing a dedicated shop, and getting its blade square to the table and its bevel dead-on is a two-minute job with a Wixey digital angle gauge. For laying out the cuts and checking the milled faces for square, a Starrett combination square you can trust to the thousandth is the reference every other measurement answers to.

Buy like you belong

The whole routine fits on an index card. Know your finished thickness and buy the quarter above it. Compute board feet at the rack and do the arithmetic before you commit. Match the grade to whether you need long clear parts or small cuttings. Confirm it is kiln-dried, and check moisture with a meter if you have one. Inspect every board for cup, bow, twist, and checks, and overbuy by fifteen to twenty percent so a bad board does not stop your build.

Do that and the rack stops being intimidating. Reading the grain of each plank before you pay is the natural next habit — covered in reading grain direction — and the milling that turns rough stock into parts leans on the starter hand-tool kit. For the gear worth owning to break down lumber, our best-of picks are the shortlist.