6x6 Actual Size
The real dimensions of a nominal 6x6, and what it's commonly used for.
| Measurement | Value |
|---|---|
| Nominal size | 6x6 |
| Actual thickness | 5-1/2" |
| Actual width | 5-1/2" |
| Board feet per linear foot | 3.667 |
| Approx. weight per linear foot | 8.17 lb (kiln-dried softwood) |
| Common uses | Large structural posts, pergola posts |
Why a 6x6 measures 5-1/2" × 5-1/2"
Like all dimensional lumber, a 6x6 starts life close to its nominal size before it's dried and planed smooth on all four sides. That process removes roughly 1/2 inch from each dimension, leaving the actual, finished size you buy at 5-1/2" × 5-1/2". This is standard across every softwood lumberyard in the US, not specific to any one supplier.
Where these numbers come from
Actual dimensions reflect the American Softwood Lumber Standard (PS 20) size for surfaced dry (S-DRY) dimension lumber. Weight is an approximate figure for kiln-dried softwood framing lumber and varies somewhat by species and moisture content.
Frequently asked questions
Is a 6x6 really 6 by 6 inches?
No -- like all dimensional lumber, the 6x6 name describes the rough size before milling. After drying and planing, the actual size is 5-1/2" × 5-1/2".
Does this size vary by species?
The actual dimension is standardized across species for a given nominal size, though weight per linear foot varies somewhat since different softwood species have different densities.
What is a 6x6 commonly used for?
Large structural posts, pergola posts.
Think we got it wrong? Let us know.
Don't see a calculator you need? Let us know.
All LumberCalcs tools
Framing & Structural
Board Foot Calculator Joist Span Calculator Plywood Calculator Rafter Calculator Rafter Length Calculator Nominal vs. Actual Lumber Sizes 1x4 Actual Size 1x6 Actual Size 1x8 Actual Size 2x4 Actual Size 2x6 Actual Size 2x8 Actual Size 2x10 Actual Size 2x12 Actual Size 4x4 Actual Size 4x6 Actual Size 6x6 Actual Size Door & Window Rough Opening Sizes Nail & Screw Size Chart Lumber Grade Guide Linear Feet, Board Feet & Cubic Feet Stud Count Calculator Header & Beam Load CalculatorFencing
Concrete for Fence Posts Calculator Fence Calculator Fence Cost Calculator Fence Picket Calculator Fence Post Calculator Fence Post Depth CalculatorFinishing & Materials
Crown Molding Calculator Lumber Cost Calculator Miter Angle Calculator Wood Movement Calculator Wood Stain Coverage Calculator Wood Weight Calculator Wood Species Hardness (Janka Scale)No calculators match your search.