Lumber Buying Basics: Understanding 4/4, Board Feet, and Wood Grades
If you’ve ever browsed hardwood lumber or talked to a sawyer and felt like they were speaking a different language — you’re not alone. Terms like “4/4 rough,” “S2S,” and “FAS” can seem confusing at first, but they’re part of a standardized system that helps buyers and sellers understand exactly what kind of wood is being offered.
This guide breaks it down so you can make informed decisions whether you're building furniture, crafting cutting boards, or just getting into woodworking.
Lumber Thickness: What Does 4/4 Mean?
Hardwood lumber is traditionally measured in quarters of an inch, based on its rough-sawn thickness before surfacing. This is known as nominal thickness — what the board started as when it came off the sawmill.
Here's a breakdown:
Nominal ThicknessNameApprox. Actual Thickness (Planed)4/4Four-quarter~13/16" to 7/8"5/4Five-quarter~1"6/4Six-quarter~1 1/4"8/4Eight-quarter~1 3/4"
Note: These are nominal sizes — once the board is planed smooth (S2S or S4S), you lose a bit of thickness. This is normal and expected in the hardwood world.
If that sounds confusing, think of it like a 2x4 from the hardware store: it’s called a 2x4, but it actually measures 1 ½" x 3 ½". Same idea here — the name sticks, even though the finished size is smaller.
Surfacing: Rough, S2S, S3S, S4S
Lumber may be sold rough or surfaced on one or more sides. Here's what those terms mean:
Rough: No surfacing. You’ll plane and flatten it yourself. (Most control, lowest cost.)
S2S (Surfaced Two Sides): Planed top and bottom.
S3S (Surfaced Three Sides): Planed top/bottom and one edge jointed.
S4S (Surfaced Four Sides): Ready to use — planed and squared on all sides.
We usually stock rough lumber so craftspeople can mill it to their exact needs, but we’re happy to S2S or S4S for you if requested.
Lumber Grades: What Is FAS, #1 Common, #2 Common?
Hardwood lumber is graded based on clear yield — how much usable wood you get once defects like knots or splits are removed. The grading system is set by the National Hardwood Lumber Association (NHLA).
Common Grades:
FAS (First and Seconds): The highest grade. Long, wide boards with minimal defects and at least 83% clear wood.
Select: Similar to FAS but may be narrower or shorter.
#1 Common: 66% clear, still great for many furniture projects.
#2 Common: 50% clear, often used in rustic or utility builds.
Most of the lumber we mill and sell is FAS or #1 Common, depending on the species and the log it came from.
Board Foot Pricing
Lumber is sold by the board foot, a volume measurement:
1 board foot = 12" × 12" × 1"
So a board that’s 6” wide, 8’ long, and 1” thick contains:
(6 × 96 × 1) / 144 = 4 board feet
We price lumber per board foot, and we’re happy to walk you through how your total is calculated at the yard.
Ask Questions, Get the Right Wood
Whether you’re new to woodworking or buying custom-milled hardwood for a specific project, we’re here to help. Ask us about species, grain, thickness, or surfacing — we’ll help you find the right board and explain how it was milled.
At Grabeldinger Firewood, we believe good lumber starts in the woods — but ends in the hands of someone who knows what they’re working with.
