Lumber Size Chart(Nominal vs Actual Dimensions)

The definitive guide to wood sizes for carpenters, contractors, and makers. Stop guessing why your 2x4 isn't 2 inches by 4 inches. Get actual dimensions for softwood, hardwood, and sheet goods in one printable chart.

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Framing Softwood

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Dimensional Lumber (Softwood)

Nominal vs Actual Dimensions • Letter

Nominal SizeActual (Inch)Actual (MM)Common Uses / Notes
1 x 23/4" x 1 1/2"19 x 38 mmTrim, Furring
1 x 33/4" x 2 1/2"19 x 64 mmBaseboards, Trim
1 x 43/4" x 3 1/2"19 x 89 mmTrim, Fascia
1 x 63/4" x 5 1/2"19 x 140 mmFencing, Shelving
1 x 83/4" x 7 1/4"19 x 184 mmShelving, Siding
1 x 103/4" x 9 1/4"19 x 235 mmTrim, Shelving
1 x 123/4" x 11 1/4"19 x 286 mmStair treads, Shelving
2 x 21 1/2" x 1 1/2"38 x 38 mmBalusters, Framing
2 x 31 1/2" x 2 1/2"38 x 64 mmFraming
2 x 41 1/2" x 3 1/2"38 x 89 mmWall Studs, Framing
2 x 61 1/2" x 5 1/2"38 x 140 mmJoists, Rafters
2 x 81 1/2" x 7 1/4"38 x 184 mmFloor Joists
2 x 101 1/2" x 9 1/4"38 x 235 mmFloor Joists, Headers
2 x 121 1/2" x 11 1/4"38 x 286 mmStair Stringers
4 x 43 1/2" x 3 1/2"89 x 89 mmPosts
4 x 63 1/2" x 5 1/2"89 x 140 mmPosts, Beams
6 x 65 1/2" x 5 1/2"140 x 140 mmHeavy Posts

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How to Use This Chart

Avoid the most common beginner mistake: measuring based on the label instead of the lumber.

Nominal vs Actual

Understand why a 2x4 isn't 2"x4". It starts that size (Rough Cut) but shrinks during drying and planing to 1.5"x3.5".

Choose the Right Wood

Use 'Dimensional' (2x4) for framing. Use 'Hardwood' (4/4, 8/4) for fine furniture. Use 'Sheet Goods' for cabinets.

Measure for Projects

Always design with ACTUAL dimensions. Three 2x4s side-by-side measure 4.5", not 6". Use the chart to plan precise cuts.

Common Applications

Which wood goes where? A quick guide to standard uses.

🏠

Home Framing

Structural lumber sizes (2x4, 2x6, 2x10) are standard for wall studs, floor joists, and headers.

  • Studs: 2x4 or 2x6
  • Joists: 2x8, 2x10, 2x12
  • Posts: 4x4, 6x6
🪑

Furniture Making

Fine woodworking uses the 'Quarter' system for thickness. 4/4 is 1" rough, surfacing to ~13/16".

  • Tabletops: 5/4 (1-1/16" finished)
  • Face Frames: 1x2 (3/4" x 1-1/2")
  • Drawer Sides: 1/2" Plywood
☀️

Decking & Outdoor

Pressure-treated lumber is often swollen from moisture. A fresh 2x6 deck board might measure fuller than a kiln-dried one.

  • Deck Boards: 5/4 x 6
  • Posts: 4x4 or 6x6
  • Account for shrinkage gaps

Actual vs Nominal Lumber Sizes Explained

Why is lumber smaller than its name? Understanding the drying and surfacing process is key to precise measurements.

Construction

Dimensional (Actual Size)

Commonly used for framing. A 2x4 nominal is 1.5" x 3.5" actual. A 1x6 is 0.75" x 5.5". Always plan your project using these actual dimensions.

Fine Woodworking

Hardwood (Quarter System)

Sold by the 'Quarter'. 4/4 is 1" rough, 8/4 is 2" rough. After surfacing (S2S/S4S), thickness typically drops by 3/16".

Cabinetry

Sheet Goods & Plywood

Nominal 3/4" plywood is usually 23/32" (18mm). This small difference is critical for creating tight-fitting dado joints in cabinetry.

Lumber Weight Estimator

Estimates for standard Pine/Fir. Wet (Green) wood is much heavier. Plan your hardware store trip accordingly.

Size (8ft Length)Dry Weight (Approx)Green/Wet Weight (Approx)
2x4 (8ft)~9 lbs~13 lbs
2x6 (8ft)~14 lbs~20 lbs
2x8 (8ft)~19 lbs~27 lbs
2x10 (8ft)~24 lbs~35 lbs
2x12 (8ft)~29 lbs~42 lbs
4x4 (8ft)~22 lbs~35 lbs

Common Molding & Trim Sizes

Trim profiles have their own "nominal" logic. Know the actual sizes before you buy.

TypeNominal SizeActual Size
Baseboard (Speed Base)1x49/16" x 3-1/4"
Casing (Door Trim)1x39/16" x 2-1/4"
Quarter Round3/4"3/4" x 3/4"
Shoe Molding1/2"1/2" x 3/4"

Fastener Guide for 2x Lumber

What length screw/nail do you need to join 2x4s? Use this guide to choose the right fastener.

ApplicationFastener LengthType
Framing (2x4 to 2x4)3" to 3-1/2"16d Common Nail
Decking (5/4 Board)2-1/2"Deck Screw
Sheathing (Plywood)2" to 2-1/2"8d Nail / Ring Shank
Drywall to Stud1-1/4"Drywall Screw (Coarse)

How to Calculate Board Feet

Hardwood is sold by volume, not length. Understand the pricing unit used by lumber yards.

Formula: (Thickness" x Width" x Length") / 144

Example: One 1x6 board that is 8 feet long.

  • Thickness: 1 inch
  • Width: 6 inches
  • Length: 96 inches (8 ft)
  • Calculation: (1 x 6 x 96) / 144 = 4 Board Feet

Tip: Always buy extra (10-20%) to account for defects and waste when working with hardwood.

Frequently Asked Questions

Common questions about wood dimensions.

What is the actual size of a 2x4?
A standard 2x4 board's actual dimensions are 1.5 inches by 3.5 inches. The '2x4' name is its nominal size, referring to its rough-cut dimensions before drying and planing.
What are the actual dimensions of a 1x6?
A 1x6 board actually measures 3/4 inch by 5-1/2 inches. Like most dimensional lumber, the actual size is smaller than the nominal name due to the surfacing process.
Are 4x4 posts actually 4 inches?
No, a nominal 4x4 post actually measures 3.5 inches by 3.5 inches. If you are digging holes or using post caps, always plan for the 3.5-inch actual width.
What is the actual size of 2x6, 2x8, and 2x10 lumber?
2x6 is actually 1.5" x 5.5". 2x8 is 1.5" x 7.25". 2x10 is 1.5" x 9.25". Note that once you go above 6 inches nominal width, the 'shrinkage' increases from 0.5" to 0.75".
Why is lumber smaller than its nominal name?
Lumber starts at the full nominal size when freshly cut (green). As it dries in a kiln, it shrinks. Then, it is planed smooth (surfaced) on all sides, removing more material to reach its final uniform actual size.
What is a 'board foot'?
A board foot is a volume measurement used for hardwood. One board foot equals 144 cubic inches (typically 12" wide x 12" long x 1" thick).