What Does 8/4 Lumber Mean? Lumber Thickness Explained
If you’ve ever visited a lumber yard or browsed hardwood listings online, you’ve probably seen terms like 4/4, 6/4, or 8/4 lumber. For beginners and even experienced DIYers, these measurements can be confusing at first. Understanding what 8/4 lumber means is essential when planning furniture builds, cabinetry, or structural woodworking projects.
In this guide, we’ll break down 8/4 lumber sizing, explain how it differs from standard dimensional lumber, and help you decide when it’s the right choice for your next project.
What Is 8/4 Lumber?
8/4 lumber (read as “eight-quarter”) refers to the thickness of rough-sawn hardwood boards before they are planed smooth.
8/4 = 8 quarters of an inch
Each quarter equals ¼ inch
8 × ¼ inch = 2 inches thick (rough-sawn)
After milling, drying, and planing, 8/4 lumber typically finishes at about 1¾ inches thick, depending on how much material is removed during surfacing.
👉 Key takeaway:
8/4 lumber is not a finished size—it’s a rough thickness measurement used primarily for hardwoods.
8/4 Lumber vs Dimensional Lumber
Many people confuse 8/4 lumber with common construction lumber like 2×8 or 2×4 boards, but they are very different.
Hardwood dealers use the quarter system, while construction lumber uses nominal sizing that changes after milling.
What Is 8/4 Lumber Used For?
Because of its thickness and strength, 8/4 lumber is ideal for projects where durability and appearance matter.
Common uses include:
Solid wood tables and desks
Workbench tops
Stair treads
Bed frames
Countertops
Heavy-duty shelving
Structural furniture components
Woodworkers choose 8/4 boards when they need extra thickness for joinery, shaping, or strength.
How Thick Is 8/4 Lumber After Planing?
Rough-sawn 8/4 boards start at approximately 2 inches thick. After drying and planing:
S4S (surfaced four sides): ~1¾ inches
Custom milling: Thickness may vary
If your project requires a true 2-inch thickness, you may need to start with 10/4 lumber instead.
How to Calculate Board Feet for 8/4 Lumber
Hardwoods like 8/4 lumber are sold by the board foot, not by linear foot.
Board Foot Formula:
(Thickness × Width × Length) ÷ 144
Example:
An 8/4 board (2") × 8" wide × 6' long:
(2 × 8 × 72) ÷ 144 = 8 board feet
Knowing this helps you estimate material costs accurately before purchasing.
Is 8/4 Lumber More Expensive?
Yes—8/4 lumber typically costs more than thinner boards because:
It uses more raw material
Takes longer to dry properly
Is heavier and harder to process
However, it often saves time and effort by eliminating glue-ups or laminations for thick parts.
When Should You Choose 8/4 Lumber?
Choose 8/4 lumber if:
Your project requires strength and thickness
You want solid, one-piece construction
You plan on deep joinery or shaping
Visual impact and durability matter
For lighter projects, 4/4 or 6/4 lumber may be more economical.
Final Thoughts
Understanding what 8/4 lumber means helps you choose the right material, avoid costly mistakes, and build projects that last. Whether you’re crafting furniture, building a workbench, or designing custom wood features, 8/4 lumber offers strength, stability, and versatility that thinner boards simply can’t match.
For high-quality hardwood options and expert guidance, explore premium lumber selections at greeniemountain.com and choose the right thickness for your next woodworking project.
