Lumber Dimensions And Size Measurements

Maybe your like

Skip to main content.

Products

Back
Decking
Siding & Cladding
Railing
Flooring
Fencing
Ceiling & Soffit
Roofing
Framing
Trim & Molding
Turning Blanks
Live-Edge Slabs
Hardwood Lumber
Accessories
Custom
Sales & Specials
Catalogs
Terms of Sale
Canadian Customers
Madera en Español
Photos & Videos

Contact

Back
General Contact
Get a Quote
Become an Advantage Pro
Press Inquiries

About Us

Back
About Us
Testimonials
Wholesale
Shipping Info
Tour Our Mills
News & Events
Contests
Blog
Careers
Español

Education

Back
FAQ
Videos
Profiles & Sizes
Sawn Lumber
How-To Guides
Janka Hardness
Span Charts
Woodipedia
DeckBusters™
Environment
FSC®
Wood Allergens

Sale

Back
Decking Sale
Siding Sale
Ceiling Sale
Flooring Sale
Hardwood Lumber Sale
Turning Blank Sale
Composite Decking Sale
Sale Terms

Phone Hours

Monday–Friday 8:30am–8pm EST Saturday 8am–3pm EST Sunday Closed

Mill Hours See Complete Hours 12 Days of Christmas Sale: 12% Off

Luxury Building Materials for All Projects

Starting At $6/lf

Ipe

Starting At $4/lf

Cumaru

Starting At $3/lf

TigerwoodMahoganyGarapa

Starting At $2/lf

Teak

Starting At $5–7/lf

TimberTech® PVC

Starting At $3–10/lf

Trex®

Starting At $3–7/lf

Deckorators®

Starting At $2/lf

Thermo

Free Shipping on Select OrdersSee Sale Terms & Conditions

Project Design & Planning

Get Free Expert Help

Lumber is generally sized according to thickness, as in the case of rough sawn lumber, or in specific widths, thicknesses and/or lengths as in the case of dimensional lumber. Here we will define each to help you better understand the sizing methods used when referring to lumber "size".

Dimensional Sizing

This measuring method is probably the most recognized by the average person. It is used in almost all "Do-It-Yourself" type stores that sell lumber, or any place selling lumber for construction purposes. We recognize such “sizes” as 2x4, 2x6, 4x4, 1x2, etc. This measurement refers to the thickness and width of the lumber, with the length varying. In reality, these measurements are not a true measurement of the lumber thickness or width. The true measurement of a 2x4 is actually about 1.5″ x 3.5″. When the board is first rough sawn from the log, it is a true 2x4, but the drying process and planing of the board reduce it to the finished 1.5″ x 3.5″ size. The lumber is then sold as a “2x4” because the cost of the drying and machining are figured in. It is also much easier to refer to a board as a “2x4”, rather than a “1.5 x 3.5”.

Below you can see the most common decking and siding sizes we offer:

Nominal Size	Actual Size (Imperial)	Actual Size (Metric)
1x4	0.75″ x 3.50″	19mm x 90mm
1x5	0.75″ x 4.72″	19mm x 120mm
1x6	0.75″ x 5.50″	19mm x 140mm
1x4 +Plus®	0.83″ x 3.50″	21mm x 90mm
1x5 +Plus®	0.83″ x 4.72″	21mm x 120mm
1x6 +Plus®	0.83″ x 5.50″	21mm x 140mm
1x6 +Plus® XW™	0.83″ x 5.70″	21mm x 145mm
5/4x4	1.00″ x 3.50″	25mm x 90mm
5/4x5	1.00″ x 4.72″	25mm x 120mm
5/4x6	1.00″ x 5.50″	25mm x 140mm
5/4x8	1.00″ x 7.25″	25mm x 184mm
5/4x10	1.00″ x 9.25″	25mm x 235mm
5/4x12	1.00″ x 11.25″	25mm x 286mm
2x2	1.50″ x 1.50″	38mm x 38mm
2x4	1.50″ x 3.50″	38mm x 90mm
2x6	1.50″ x 5.50″	38mm x 140mm
2x8	1.50″ x 7.25″	38mm x 184mm
2x10	1.50″ x 9.25″	38mm x 235mm
2x12	1.50″ x 11.25″	38mm x 286mm
3x4	2.50″ x 3.50″	64mm x 90mm
3x6	2.50″ x 5.50″	64mm x 140mm
3x8	2.50″ x 7.25″	64mm x 184mm
3x10	2.50″ x 9.25″	64mm x 235mm
3x12	2.50″ x 11.25″	64mm x 286mm
4x4	3.50″ x 3.50″	90mm x 90mm
6x6	5.50″ x 5.50″	140mm x 140mm

Decking and siding is sold in linear feet. Use the calculator below to convert the square footage of your project into linear feet:

Your Square Footage Linear Footage for x6 Standard or Pre-Grooved Boards Linear Footage for x4 Standard or Pre-Grooved Boards Linear Footage for x6 T&G Boards Linear Footage for x4 T&G Boards

“Quarters” Sizing

In the case of rough sawn lumber, the "Quarters" sizing method is usually used by mills that sell rough lumber for woodworking purposes. The "Quarters" method refers only to the thickness of the wood as widths and lengths vary depending on the log the wood is cut from. Generally, a woodworker will plane the boards to the desired thickness and most likely rip the boards and glue them up into joined panels to get the desired width. Rough sawn lumber comes in "true" thicknesses as reflected by the "quarters" size. Lumber sized according to "Quarters" reflects the number of quarters of an inch thick the lumber is. To figure the thickness of a board referenced in "quarters" sizes, simply divide the second number (4) into the first number. The second number (4) means "quarters of an inch", or "quarters". So, a "4/4" board is four quarters, or 1 inch thick, an "8/4" board is eight quarters, or 2 inches thick, a "10/4" board is ten quarters, or 2.5 inches thick, etc.

Board Foot Sizing

Board Foot: Rough sawn lumber is usually sold by the "board foot" (bd. ft.). A board foot is equal to a piece of wood 12 inches long x 12 inches wide and 1 inch thick, or 144 cubic inches. To figure the board foot measurement of a piece of wood, multiply the length x width x thickness in inches, then divide by 144.

The calculator below will tell you how many board feet are in a piece of lumber based on its thickness, width, and length:

Thickness (in inches) Width (in inches) Length (in feet) Board Feet