What is the actual size of a 2×6?
A 2×6 actually measures 1-1/2 × 5-1/2 inches (about 38 × 140 mm) once it is dried and planed, so an 8 ft 2×6 billed as 8 board feet holds 5.5 board feet of wood.
How to work it out
- Nominal 2×6 → dressed dry to 1-1/2 × 5-1/2 in (PS 20 standard sizes)
- Billed: 2 × 6 × 8 ft ÷ 12 = 8 board feet · Actual: 1.5 × 5.5 × 8 ft ÷ 12 = 5.5 board feet (69%)
The 5½ in face width is the number to use when laying out 2×6 decking — rows are counted on 5½ in plus the gap — and 2×6 exterior walls are 5½ in deep for insulation.
Adjust for your project
More options: L · Qty
- Actual thickness (decimal)
- 1.5 in
- Actual width (decimal)
- 5.5 in
- Board feet (nominal — what a board-foot price is charged on)
- 8 board feet
- Board feet (actual volume)
- 5.5 board feet
- Wood you get vs. what you pay for (if priced by the board foot)
- 69%
- Actual volume
- 0.458 cu ft
- Green (unseasoned) and rough-sawn lumber is larger than these dry, surfaced sizes. Pressure-treated lumber is often sold wet and shrinks slightly as it dries.
Billed vs actual board feet for a stack of 8 ft 2×6s
| Number of 2×6×8s | Board feet (nominal — what a board-foot price is charged on) | Board feet (actual volume) | Actual volume |
|---|---|---|---|
| 1 | 8 board feet | 5.5 board feet | 0.458 cu ft |
| 10 | 80 board feet | 55 board feet | 4.583 cu ft |
| 25 | 200 board feet | 137.5 board feet | 11.458 cu ft |
| 50 | 400 board feet | 275 board feet | 22.917 cu ft |
| 100 | 800 board feet | 550 board feet | 45.833 cu ft |
What to know about a 2×6’s actual size
- Deck rows use 5½ in plus the gap. With a gap of about ⅛–¼ in, each 2×6 deck board covers roughly 5⅝–5¾ in, so a 16 ft wide deck takes about 34 rows. The 12x16 deck board count runs the numbers for a common size.
- 2×6 walls are 5½ in deep. That extra 2 in over a 2×4 wall is room for thicker insulation, and it is why window and door jambs for 2×6 walls need extensions or wider jamb stock.
- Joists and rafters span on 5½ in. Span tables are built on the dressed depth, not 6 in, so do not round up when you compare a 2×6 with a 2×8 (7¼ in deep).
- Doubled 2×6s are 3 in thick. A pair of 2×6s makes a 3 × 5½ in header or beam — enough for small window openings in many plans.
For pricing, a 2×6×8 is billed as 8 board feet — one per foot. The post-sized version of the same rule is what is the actual size of a 4x4.
Different size? Use the full Lumber Dimensions Calculator.
What you’ll need
- 25 ft tape measureBudget price
A 25 ft tape with a stiff blade and a readable 1/16 in scale covers everything from cut lists to deck layout.
See options on Amazon (opens in a new tab) - Speed square (7 in)Budget price
Marks square and angled crosscuts and doubles as a saw guide for a circular saw. The degree scale is handy for rafters and stair angles.
See options on Amazon (opens in a new tab) - Circular saw (7¼ in)Mid-range price
The most versatile first power saw: crosscuts framing lumber, rips boards and, with a straightedge, breaks down plywood sheets.
See options on Amazon (opens in a new tab)
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Frequently asked questions
What is the actual size of a 2×8?
A 2×8 measures 1-1/2 × 7-1/4 inches (about 38 × 184 mm) — from 8 in up, the width loses ¾ in, not ½ in.
What is the actual size of a 5/4×6 deck board?
A 5/4×6 deck board is typically 1 × 5-1/2 inches (about 25 × 140 mm), with rounded edges; exact thickness varies by mill.
What is the actual size of a 1×6 board?
A 1×6 measures 3/4 × 5-1/2 inches (about 19 × 140 mm) — the same 5½ in face as a 2×6.
Other common sizes
- What is the actual size of a 2x4 — 1-1/2 × 3-1/2 in
- What is the actual size of a 4x4 — 3-1/2 × 3-1/2 in
Sources
- NIST, Voluntary Product Standard PS 20-20, American Softwood Lumber Standard (Rev. 1, 2021) (opens in a new tab) — Table 3: minimum dry and green dressed sizes of boards, dimension and timbers (timbers 5 in and thicker: 1/2 in under nominal, green).
- National Hardwood Lumber Association, Rules for the Measurement & Inspection of Hardwood & Cypress (2019) (opens in a new tab) — Paragraph 14: standard surfaced (S2S) thicknesses — 4/4 to 13/16 in, 5/4 to 1-1/16, 6/4 to 1-5/16, 8/4 to 1-3/4, 12/4 to 2-3/4.
- American Hardwood Export Council, The Illustrated Guide to American Hardwood Lumber Grades (opens in a new tab) — Rough quarter thicknesses and the 3/16 in / 1/4 in surfacing allowance.
- NELMA, Standard Grading Rules, Section 4: Other Board Grades (2024) (opens in a new tab) — Standard Shop thicknesses: 5/4 surfaced to 1-5/32 in.